rfc9143.original.xml   rfc9143.xml 
<?xml version='1.0' encoding='utf-8'?> <?xml version="1.0" encoding="UTF-8"?>
<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" category="std" docNa
me="draft-ietf-mmusic-rfc8843bis-09" indexInclude="true" ipr="pre5378Trust200902 <!DOCTYPE rfc [
" scripts="Common,Latin" sortRefs="true" submissionType="IETF" symRefs="true" to <!ENTITY nbsp "&#160;">
cDepth="3" tocInclude="true" obsoletes="8843" updates="3264, 5888, 7941" xml:lan <!ENTITY zwsp "&#8203;">
g="en"> <!ENTITY nbhy "&#8209;">
<!ENTITY wj "&#8288;">
]>
<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" docName="draft-ietf-
mmusic-rfc8843bis-05" number="9143" ipr="pre5378Trust200902" sortRefs="true" sub
missionType="IETF" category="std" consensus="true" symRefs="true" tocDepth="3" t
ocInclude="true" obsoletes="8843" updates="3264, 5888, 7941" xml:lang="en" scrip
ts="Common,Latin" indexInclude="true">
<front> <front>
<title abbrev="Bundled Media">Negotiating Media Multiplexing Using the Sessi on Description Protocol (SDP)</title> <title abbrev="Bundled Media">Negotiating Media Multiplexing Using the Sessi on Description Protocol (SDP)</title>
<seriesInfo name="RFC" value="8843" stream="IETF"/> <seriesInfo name="RFC" value="9143"/>
<author initials="C." surname="Holmberg" fullname="Christer Holmberg"> <author initials="C." surname="Holmberg" fullname="Christer Holmberg">
<organization showOnFrontPage="true">Ericsson</organization> <organization>Ericsson</organization>
<address> <address>
<postal> <postal>
<street>Hirsalantie 11</street> <street>Hirsalantie 11</street>
<code>02420</code> <code>02420</code>
<city>Jorvas</city> <city>Jorvas</city>
<country>Finland</country> <country>Finland</country>
</postal> </postal>
<email>christer.holmberg@ericsson.com</email> <email>christer.holmberg@ericsson.com</email>
</address> </address>
</author> </author>
<author fullname="Harald Tveit Alvestrand" initials="H." surname="Alvestrand "> <author fullname="Harald Tveit Alvestrand" initials="H." surname="Alvestrand ">
<organization showOnFrontPage="true">Google</organization> <organization>Google</organization>
<address> <address>
<postal> <postal>
<street>Kungsbron 2</street> <street>Kungsbron 2</street>
<city>Stockholm</city> <city>Stockholm</city>
<code>11122</code> <code>11122</code>
<country>Sweden</country> <country>Sweden</country>
</postal> </postal>
<email>harald@alvestrand.no</email> <email>harald@alvestrand.no</email>
</address> </address>
</author> </author>
<author fullname="Cullen Jennings" initials="C." surname="Jennings"> <author fullname="Cullen Jennings" initials="C." surname="Jennings">
<organization showOnFrontPage="true">Cisco</organization> <organization>Cisco</organization>
<address> <address>
<postal> <postal>
<street>400 3rd Avenue SW, Suite 350</street> <street>400 3rd Avenue SW</street>
<extaddr>Suite 350</extaddr>
<city>Calgary</city> <city>Calgary</city>
<region>AB</region> <region>AB</region>
<code>T2P 4H2</code> <code>T2P 4H2</code>
<country>Canada</country> <country>Canada</country>
</postal> </postal>
<email>fluffy@iii.ca</email> <email>fluffy@iii.ca</email>
</address> </address>
</author> </author>
<date day="05" month="12" year="2021"/> <date month="February" year="2022"/>
<area>Transport</area> <area>Transport</area>
<workgroup>MMUSIC Working Group</workgroup> <workgroup>MMUSIC Working Group</workgroup>
<keyword>RTP</keyword> <keyword>RTP</keyword>
<keyword>SDP</keyword> <keyword>SDP</keyword>
<keyword>Bundle</keyword> <keyword>Bundle</keyword>
<keyword>Multiplexing</keyword> <keyword>Multiplexing</keyword>
<keyword>RTCWEB</keyword> <keyword>RTCWEB</keyword>
<keyword>CLUE</keyword> <keyword>CLUE</keyword>
<keyword>RTCWEB</keyword> <keyword>RTCWEB</keyword>
<keyword>MMUSIC</keyword> <keyword>MMUSIC</keyword>
<keyword>AVT</keyword> <keyword>AVT</keyword>
<keyword>WEB</keyword> <keyword>WEB</keyword>
<keyword>Browser</keyword> <keyword>Browser</keyword>
<abstract pn="section-abstract"> <abstract>
<t indent="0" pn="section-abstract-1"> <t>
This specification defines a new Session Description This specification defines a new Session Description
Protocol (SDP) Grouping Framework extension called 'BUNDLE'. Protocol (SDP) Grouping Framework extension called 'BUNDLE'.
The extension can be used with the SDP offer/answer mechanism The extension can be used with the SDP offer/answer mechanism
to negotiate the usage of a single transport (5-tuple) for to negotiate the usage of a single transport (5-tuple) for
sending and receiving media described by multiple SDP media descriptions sending and receiving media described by multiple SDP media descriptions
("m=" sections). Such transport is referred to as a BUNDLE transport, ("m=" sections). Such transport is referred to as a "BUNDLE transport",
and the media is referred to as bundled media. The "m=" sections that and the media is referred to as "bundled media". The "m=" sections that
use the BUNDLE transport form a BUNDLE group. use the BUNDLE transport form a BUNDLE group.
</t> </t>
<t indent="0" pn="section-abstract-2"> <t>
This specification defines a new RTP Control Protocol (RTCP) Source This specification defines a new RTP Control Protocol (RTCP) Source
Description (SDES) item and a new RTP header extension.</t> Description (SDES) item and a new RTP header extension.</t>
<t indent="0" pn="section-abstract-3"> <t>
This specification updates RFCs 3264, 5888, and 7941. This specification updates RFCs 3264, 5888, and 7941.
</t> </t>
<t indent="0" pn="section-abstract-4"> <t>
This specification obsoletes RFC 8843. This specification obsoletes RFC 8843.
</t> </t>
</abstract> </abstract>
<boilerplate>
<section anchor="status-of-memo" numbered="false" removeInRFC="false" toc=
"exclude" pn="section-boilerplate.1">
<name slugifiedName="name-status-of-this-memo">Status of This Memo</name
>
<t indent="0" pn="section-boilerplate.1-1">
This is an Internet Standards Track document.
</t>
<t indent="0" pn="section-boilerplate.1-2">
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by
the Internet Engineering Steering Group (IESG). Further
information on Internet Standards is available in Section 2 of
RFC 7841.
</t>
<t indent="0" pn="section-boilerplate.1-3">
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
<eref target="https://www.rfc-editor.org/info/rfc8843" brackets="non
e"/>.
</t>
</section>
<section anchor="copyright" numbered="false" removeInRFC="false" toc="excl
ude" pn="section-boilerplate.2">
<name slugifiedName="name-copyright-notice">Copyright Notice</name>
<t indent="0" pn="section-boilerplate.2-1">
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
</t>
<t indent="0" pn="section-boilerplate.2-2">
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<eref target="https://trustee.ietf.org/license-info" brackets="none
"/>) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.
</t>
<t indent="0" pn="section-boilerplate.2-3">
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s)
controlling the copyright in such materials, this document may not
be modified outside the IETF Standards Process, and derivative
works of it may not be created outside the IETF Standards Process,
except to format it for publication as an RFC or to translate it
into languages other than English.
</t>
</section>
</boilerplate>
<toc>
<section anchor="toc" numbered="false" removeInRFC="false" toc="exclude" p
n="section-toc.1">
<name slugifiedName="name-table-of-contents">Table of Contents</name>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="section-to
c.1-1">
<li pn="section-toc.1-1.1">
<t indent="0" pn="section-toc.1-1.1.1"><xref derivedContent="1" form
at="counter" sectionFormat="of" target="section-1"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-introduction">Introduction</xref><
/t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.1.2">
<li pn="section-toc.1-1.1.2.1">
<t indent="0" keepWithNext="true" pn="section-toc.1-1.1.2.1.1"><
xref derivedContent="1.1" format="counter" sectionFormat="of" target="section-1.
1"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-ba
ckground">Background</xref></t>
</li>
<li pn="section-toc.1-1.1.2.2">
<t indent="0" keepWithNext="true" pn="section-toc.1-1.1.2.2.1"><
xref derivedContent="1.2" format="counter" sectionFormat="of" target="section-1.
2"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-bu
ndle-mechanism">BUNDLE Mechanism</xref></t>
</li>
<li pn="section-toc.1-1.1.2.3">
<t indent="0" keepWithNext="true" pn="section-toc.1-1.1.2.3.1"><
xref derivedContent="1.3" format="counter" sectionFormat="of" target="section-1.
3"/>.  <xref derivedContent="" format="title" sectionFormat="of" target="name-pr
otocol-extensions">Protocol Extensions</xref></t>
</li>
<li pn="section-toc.1-1.1.2.4">
<t indent="0" pn="section-toc.1-1.1.2.4.1"><xref derivedContent=
"1.4" format="counter" sectionFormat="of" target="section-1.4"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="sec-changes-8843">Changes f
rom RFC 8843</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.2">
<t indent="0" pn="section-toc.1-1.2.1"><xref derivedContent="2" form
at="counter" sectionFormat="of" target="section-2"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-terminology">Terminology</xref></t
>
</li>
<li pn="section-toc.1-1.3">
<t indent="0" pn="section-toc.1-1.3.1"><xref derivedContent="3" form
at="counter" sectionFormat="of" target="section-3"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-conventions">Conventions</xref></t
>
</li>
<li pn="section-toc.1-1.4">
<t indent="0" pn="section-toc.1-1.4.1"><xref derivedContent="4" form
at="counter" sectionFormat="of" target="section-4"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-applicability-statement">Applicabi
lity Statement</xref></t>
</li>
<li pn="section-toc.1-1.5">
<t indent="0" pn="section-toc.1-1.5.1"><xref derivedContent="5" form
at="counter" sectionFormat="of" target="section-5"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-sdp-grouping-framework-bund">SDP G
rouping Framework BUNDLE Extension</xref></t>
</li>
<li pn="section-toc.1-1.6">
<t indent="0" pn="section-toc.1-1.6.1"><xref derivedContent="6" form
at="counter" sectionFormat="of" target="section-6"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-sdp-bundle-only-attribute">SDP 'bu
ndle-only' Attribute</xref></t>
</li>
<li pn="section-toc.1-1.7">
<t indent="0" pn="section-toc.1-1.7.1"><xref derivedContent="7" form
at="counter" sectionFormat="of" target="section-7"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-sdp-offer-answer-procedures">SDP O
ffer/Answer Procedures</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.7.2">
<li pn="section-toc.1-1.7.2.1">
<t indent="0" pn="section-toc.1-1.7.2.1.1"><xref derivedContent=
"7.1" format="counter" sectionFormat="of" target="section-7.1"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-generic-sdp-considerat
ions">Generic SDP Considerations</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.7.2.1.2">
<li pn="section-toc.1-1.7.2.1.2.1">
<t indent="0" pn="section-toc.1-1.7.2.1.2.1.1"><xref derived
Content="7.1.1" format="counter" sectionFormat="of" target="section-7.1.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-connection
-data-c">Connection Data ("c=")</xref></t>
</li>
<li pn="section-toc.1-1.7.2.1.2.2">
<t indent="0" pn="section-toc.1-1.7.2.1.2.2.1"><xref derived
Content="7.1.2" format="counter" sectionFormat="of" target="section-7.1.2"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-bandwidth-
b">Bandwidth ("b=")</xref></t>
</li>
<li pn="section-toc.1-1.7.2.1.2.3">
<t indent="0" pn="section-toc.1-1.7.2.1.2.3.1"><xref derived
Content="7.1.3" format="counter" sectionFormat="of" target="section-7.1.3"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-attributes
-a">Attributes ("a=")</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.7.2.2">
<t indent="0" pn="section-toc.1-1.7.2.2.1"><xref derivedContent=
"7.2" format="counter" sectionFormat="of" target="section-7.2"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-generating-the-initial
-bundle-">Generating the Initial BUNDLE offer</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.7.2.2.2">
<li pn="section-toc.1-1.7.2.2.2.1">
<t indent="0" pn="section-toc.1-1.7.2.2.2.1.1"><xref derived
Content="7.2.1" format="counter" sectionFormat="of" target="section-7.2.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-suggesting
-the-offerer-tagg">Suggesting the Offerer-Tagged 'm=' Section</xref></t>
</li>
<li pn="section-toc.1-1.7.2.2.2.2">
<t indent="0" pn="section-toc.1-1.7.2.2.2.2.1"><xref derived
Content="7.2.2" format="counter" sectionFormat="of" target="section-7.2.2"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-example-in
itial-bundle-offer">Example: Initial BUNDLE offer</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.7.2.3">
<t indent="0" pn="section-toc.1-1.7.2.3.1"><xref derivedContent=
"7.3" format="counter" sectionFormat="of" target="section-7.3"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-generating-the-sdp-ans
wer">Generating the SDP Answer</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.7.2.3.2">
<li pn="section-toc.1-1.7.2.3.2.1">
<t indent="0" pn="section-toc.1-1.7.2.3.2.1.1"><xref derived
Content="7.3.1" format="counter" sectionFormat="of" target="section-7.3.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-answerer-s
election-of-tagge">Answerer Selection of Tagged 'm=' Sections</xref></t>
</li>
<li pn="section-toc.1-1.7.2.3.2.2">
<t indent="0" pn="section-toc.1-1.7.2.3.2.2.1"><xref derived
Content="7.3.2" format="counter" sectionFormat="of" target="section-7.3.2"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-moving-a-m
edia-description-">Moving a Media Description Out of a BUNDLE Group</xref></t>
</li>
<li pn="section-toc.1-1.7.2.3.2.3">
<t indent="0" pn="section-toc.1-1.7.2.3.2.3.1"><xref derived
Content="7.3.3" format="counter" sectionFormat="of" target="section-7.3.3"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-rejecting-
a-media-descripti">Rejecting a Media Description in a BUNDLE Group</xref></t>
</li>
<li pn="section-toc.1-1.7.2.3.2.4">
<t indent="0" pn="section-toc.1-1.7.2.3.2.4.1"><xref derived
Content="7.3.4" format="counter" sectionFormat="of" target="section-7.3.4"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-example-sd
p-answer">Example: SDP Answer</xref></t>
</li>
<li pn="section-toc.1-1.7.2.3.2.5">
<t indent="0" pn="section-toc.1-1.7.2.3.2.5.1"><xref derived
Content="7.3.5" format="counter" sectionFormat="of" target="section-7.3.5"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="sec-sdp-oa-ans-
8843">RFC 8843 Considerations</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.7.2.4">
<t indent="0" pn="section-toc.1-1.7.2.4.1"><xref derivedContent=
"7.4" format="counter" sectionFormat="of" target="section-7.4"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-offerer-processing-of-
the-s">Offerer Processing of the SDP Answer</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.7.2.4.2">
<li pn="section-toc.1-1.7.2.4.2.1">
<t indent="0" pn="section-toc.1-1.7.2.4.2.1.1"><xref derived
Content="7.4.1" format="counter" sectionFormat="of" target="section-7.4.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="sec-sdp-oa-off-
8843">RFC 8843 Considerations</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.7.2.5">
<t indent="0" pn="section-toc.1-1.7.2.5.1"><xref derivedContent=
"7.5" format="counter" sectionFormat="of" target="section-7.5"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-modifying-the-session"
>Modifying the Session</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.7.2.5.2">
<li pn="section-toc.1-1.7.2.5.2.1">
<t indent="0" pn="section-toc.1-1.7.2.5.2.1.1"><xref derived
Content="7.5.1" format="counter" sectionFormat="of" target="section-7.5.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-adding-a-m
edia-description-">Adding a Media Description to a BUNDLE Group</xref></t>
</li>
<li pn="section-toc.1-1.7.2.5.2.2">
<t indent="0" pn="section-toc.1-1.7.2.5.2.2.1"><xref derived
Content="7.5.2" format="counter" sectionFormat="of" target="section-7.5.2"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-moving-a-m
edia-description-o">Moving a Media Description Out of a BUNDLE Group</xref></t>
</li>
<li pn="section-toc.1-1.7.2.5.2.3">
<t indent="0" pn="section-toc.1-1.7.2.5.2.3.1"><xref derived
Content="7.5.3" format="counter" sectionFormat="of" target="section-7.5.3"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-disabling-
a-media-descripti">Disabling a Media Description in a BUNDLE Group</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.7.2.6">
<t indent="0" pn="section-toc.1-1.7.2.6.1"><xref derivedContent=
"7.6" format="counter" sectionFormat="of" target="section-7.6"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="sec-sdp-oa-sip">SIP Conside
rations</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.8">
<t indent="0" pn="section-toc.1-1.8.1"><xref derivedContent="8" form
at="counter" sectionFormat="of" target="section-8"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-protocol-identification">Protocol
Identification</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.8.2">
<li pn="section-toc.1-1.8.2.1">
<t indent="0" pn="section-toc.1-1.8.2.1.1"><xref derivedContent=
"8.1" format="counter" sectionFormat="of" target="section-8.1"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-stun-dtls-and-srtp">ST
UN, DTLS, and SRTP</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.9">
<t indent="0" pn="section-toc.1-1.9.1"><xref derivedContent="9" form
at="counter" sectionFormat="of" target="section-9"/>.  <xref derivedContent="" f
ormat="title" sectionFormat="of" target="name-rtp-considerations">RTP Considerat
ions</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.9.2">
<li pn="section-toc.1-1.9.2.1">
<t indent="0" pn="section-toc.1-1.9.2.1.1"><xref derivedContent=
"9.1" format="counter" sectionFormat="of" target="section-9.1"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-single-rtp-session">Si
ngle RTP Session</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.9.2.1.2">
<li pn="section-toc.1-1.9.2.1.2.1">
<t indent="0" pn="section-toc.1-1.9.2.1.2.1.1"><xref derived
Content="9.1.1" format="counter" sectionFormat="of" target="section-9.1.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-payload-ty
pe-pt-value-reuse">Payload Type (PT) Value Reuse</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.9.2.2">
<t indent="0" pn="section-toc.1-1.9.2.2.1"><xref derivedContent=
"9.2" format="counter" sectionFormat="of" target="section-9.2"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-associating-rtp-rtcp-s
tream">Associating RTP/RTCP Streams with the Correct SDP Media Description</xref
></t>
</li>
<li pn="section-toc.1-1.9.2.3">
<t indent="0" pn="section-toc.1-1.9.2.3.1"><xref derivedContent=
"9.3" format="counter" sectionFormat="of" target="section-9.3"/>.  <xref derived
Content="" format="title" sectionFormat="of" target="name-rtp-rtcp-multiplexing"
>RTP/RTCP Multiplexing</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.9.2.3.2">
<li pn="section-toc.1-1.9.2.3.2.1">
<t indent="0" pn="section-toc.1-1.9.2.3.2.1.1"><xref derived
Content="9.3.1" format="counter" sectionFormat="of" target="section-9.3.1"/>.  <
xref derivedContent="" format="title" sectionFormat="of" target="name-sdp-offer-
answer-procedures-2">SDP Offer/Answer Procedures</xref></t>
</li>
</ul>
</li>
</ul>
</li>
<li pn="section-toc.1-1.10">
<t indent="0" pn="section-toc.1-1.10.1"><xref derivedContent="10" fo
rmat="counter" sectionFormat="of" target="section-10"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-ice-considerations">ICE Consider
ations</xref></t>
</li>
<li pn="section-toc.1-1.11">
<t indent="0" pn="section-toc.1-1.11.1"><xref derivedContent="11" fo
rmat="counter" sectionFormat="of" target="section-11"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-dtls-considerations">DTLS Consid
erations</xref></t>
</li>
<li pn="section-toc.1-1.12">
<t indent="0" pn="section-toc.1-1.12.1"><xref derivedContent="12" fo
rmat="counter" sectionFormat="of" target="section-12"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-rtp-header-extensions-consi">RTP
Header Extensions Consideration</xref></t>
</li>
<li pn="section-toc.1-1.13">
<t indent="0" pn="section-toc.1-1.13.1"><xref derivedContent="13" fo
rmat="counter" sectionFormat="of" target="section-13"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-update-to-rfc-3264">Update to RF
C 3264</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.13.2">
<li pn="section-toc.1-1.13.2.1">
<t indent="0" pn="section-toc.1-1.13.2.1.1"><xref derivedContent
="13.1" format="counter" sectionFormat="of" target="section-13.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-original-text-from-
rfc-3264">Original Text from RFC 3264, Section 5.1, 2nd Paragraph</xref></t>
</li>
<li pn="section-toc.1-1.13.2.2">
<t indent="0" pn="section-toc.1-1.13.2.2.1"><xref derivedContent
="13.2" format="counter" sectionFormat="of" target="section-13.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-text-replacing-
rfc-3264">New Text Replacing RFC 3264, Section 5.1, 2nd Paragraph</xref></t>
</li>
<li pn="section-toc.1-1.13.2.3">
<t indent="0" pn="section-toc.1-1.13.2.3.1"><xref derivedContent
="13.3" format="counter" sectionFormat="of" target="section-13.3"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-original-text-from-
rfc-3264-">Original Text from RFC 3264, Section 8.4, 6th Paragraph</xref></t>
</li>
<li pn="section-toc.1-1.13.2.4">
<t indent="0" pn="section-toc.1-1.13.2.4.1"><xref derivedContent
="13.4" format="counter" sectionFormat="of" target="section-13.4"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-text-replacing-
rfc-3264-">New Text Replacing RFC 3264, Section 8.4, 6th Paragraph</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.14">
<t indent="0" pn="section-toc.1-1.14.1"><xref derivedContent="14" fo
rmat="counter" sectionFormat="of" target="section-14"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-update-to-rfc-5888">Update to RF
C 5888</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.14.2">
<li pn="section-toc.1-1.14.2.1">
<t indent="0" pn="section-toc.1-1.14.2.1.1"><xref derivedContent
="14.1" format="counter" sectionFormat="of" target="section-14.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-original-text-from-
rfc-5888">Original Text from RFC 5888, Section 9.2, 3rd Paragraph</xref></t>
</li>
<li pn="section-toc.1-1.14.2.2">
<t indent="0" pn="section-toc.1-1.14.2.2.1"><xref derivedContent
="14.2" format="counter" sectionFormat="of" target="section-14.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-text-replacing-
rfc-5888">New Text Replacing RFC 5888, Section 9.2, 3rd Paragraph</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.15">
<t indent="0" pn="section-toc.1-1.15.1"><xref derivedContent="15" fo
rmat="counter" sectionFormat="of" target="section-15"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-rtp-rtcp-extensions-for-ide">RTP
/RTCP Extensions for identification-tag Transport</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.15.2">
<li pn="section-toc.1-1.15.2.1">
<t indent="0" pn="section-toc.1-1.15.2.1.1"><xref derivedContent
="15.1" format="counter" sectionFormat="of" target="section-15.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-rtcp-mid-sdes-item"
>RTCP MID SDES Item</xref></t>
</li>
<li pn="section-toc.1-1.15.2.2">
<t indent="0" pn="section-toc.1-1.15.2.2.1"><xref derivedContent
="15.2" format="counter" sectionFormat="of" target="section-15.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-rtp-sdes-header-ext
ension-f">RTP SDES Header Extension For MID</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.16">
<t indent="0" pn="section-toc.1-1.16.1"><xref derivedContent="16" fo
rmat="counter" sectionFormat="of" target="section-16"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-iana-considerations">IANA Consid
erations</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.16.2">
<li pn="section-toc.1-1.16.2.1">
<t indent="0" pn="section-toc.1-1.16.2.1.1"><xref derivedContent
="16.1" format="counter" sectionFormat="of" target="section-16.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-sdes-item">New
SDES Item</xref></t>
</li>
<li pn="section-toc.1-1.16.2.2">
<t indent="0" pn="section-toc.1-1.16.2.2.1"><xref derivedContent
="16.2" format="counter" sectionFormat="of" target="section-16.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-rtp-sdes-header
-extensi">New RTP SDES Header Extension URI</xref></t>
</li>
<li pn="section-toc.1-1.16.2.3">
<t indent="0" pn="section-toc.1-1.16.2.3.1"><xref derivedContent
="16.3" format="counter" sectionFormat="of" target="section-16.3"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-sdp-attribute">
New SDP Attribute</xref></t>
</li>
<li pn="section-toc.1-1.16.2.4">
<t indent="0" pn="section-toc.1-1.16.2.4.1"><xref derivedContent
="16.4" format="counter" sectionFormat="of" target="section-16.4"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-new-sdp-group-seman
tics">New SDP Group Semantics</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.17">
<t indent="0" pn="section-toc.1-1.17.1"><xref derivedContent="17" fo
rmat="counter" sectionFormat="of" target="section-17"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-security-considerations">Securit
y Considerations</xref></t>
</li>
<li pn="section-toc.1-1.18">
<t indent="0" pn="section-toc.1-1.18.1"><xref derivedContent="18" fo
rmat="counter" sectionFormat="of" target="section-18"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-examples">Examples</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.18.2">
<li pn="section-toc.1-1.18.2.1">
<t indent="0" pn="section-toc.1-1.18.2.1.1"><xref derivedContent
="18.1" format="counter" sectionFormat="of" target="section-18.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-example-tagged-m-se
ction-se">Example: Tagged "m=" Section Selections</xref></t>
</li>
<li pn="section-toc.1-1.18.2.2">
<t indent="0" pn="section-toc.1-1.18.2.2.1"><xref derivedContent
="18.2" format="counter" sectionFormat="of" target="section-18.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-example-bundle-grou
p-reject">Example: BUNDLE Group Rejected</xref></t>
</li>
<li pn="section-toc.1-1.18.2.3">
<t indent="0" pn="section-toc.1-1.18.2.3.1"><xref derivedContent
="18.3" format="counter" sectionFormat="of" target="section-18.3"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-example-offerer-add
s-a-medi">Example: Offerer Adds a Media Description to a BUNDLE Group</xref></t>
</li>
<li pn="section-toc.1-1.18.2.4">
<t indent="0" pn="section-toc.1-1.18.2.4.1"><xref derivedContent
="18.4" format="counter" sectionFormat="of" target="section-18.4"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-example-offerer-mov
es-a-med">Example: Offerer Moves a Media Description Out of a BUNDLE Group</xref
></t>
</li>
<li pn="section-toc.1-1.18.2.5">
<t indent="0" pn="section-toc.1-1.18.2.5.1"><xref derivedContent
="18.5" format="counter" sectionFormat="of" target="section-18.5"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-example-offerer-dis
ables-a-">Example: Offerer Disables a Media Description within a BUNDLE Group</x
ref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.19">
<t indent="0" pn="section-toc.1-1.19.1"><xref derivedContent="19" fo
rmat="counter" sectionFormat="of" target="section-19"/>. <xref derivedContent=""
format="title" sectionFormat="of" target="name-references">References</xref></t
>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.19.2">
<li pn="section-toc.1-1.19.2.1">
<t indent="0" pn="section-toc.1-1.19.2.1.1"><xref derivedContent
="19.1" format="counter" sectionFormat="of" target="section-19.1"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-normative-reference
s">Normative References</xref></t>
</li>
<li pn="section-toc.1-1.19.2.2">
<t indent="0" pn="section-toc.1-1.19.2.2.1"><xref derivedContent
="19.2" format="counter" sectionFormat="of" target="section-19.2"/>.  <xref deri
vedContent="" format="title" sectionFormat="of" target="name-informative-referen
ces">Informative References</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.20">
<t indent="0" pn="section-toc.1-1.20.1"><xref derivedContent="Append
ix A" format="default" sectionFormat="of" target="section-appendix.a"/>.  <xref
derivedContent="" format="title" sectionFormat="of" target="name-design-consider
ations">Design Considerations</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="sectio
n-toc.1-1.20.2">
<li pn="section-toc.1-1.20.2.1">
<t indent="0" pn="section-toc.1-1.20.2.1.1"><xref derivedContent
="A.1" format="counter" sectionFormat="of" target="section-a.1"/>.  <xref derive
dContent="" format="title" sectionFormat="of" target="name-ua-interoperability">
UA Interoperability</xref></t>
</li>
<li pn="section-toc.1-1.20.2.2">
<t indent="0" pn="section-toc.1-1.20.2.2.1"><xref derivedContent
="A.2" format="counter" sectionFormat="of" target="section-a.2"/>.  <xref derive
dContent="" format="title" sectionFormat="of" target="name-usage-of-port-number-
value-">Usage of Port Number Value Zero</xref></t>
</li>
<li pn="section-toc.1-1.20.2.3">
<t indent="0" pn="section-toc.1-1.20.2.3.1"><xref derivedContent
="A.3" format="counter" sectionFormat="of" target="section-a.3"/>.  <xref derive
dContent="" format="title" sectionFormat="of" target="name-b2bua-and-proxy-inter
operab">B2BUA and Proxy Interoperability</xref></t>
<ul bare="true" empty="true" indent="2" spacing="compact" pn="se
ction-toc.1-1.20.2.3.2">
<li pn="section-toc.1-1.20.2.3.2.1">
<t indent="0" pn="section-toc.1-1.20.2.3.2.1.1"><xref derive
dContent="A.3.1" format="counter" sectionFormat="of" target="section-a.3.1"/>.  
<xref derivedContent="" format="title" sectionFormat="of" target="name-traffic-p
olicing">Traffic Policing</xref></t>
</li>
<li pn="section-toc.1-1.20.2.3.2.2">
<t indent="0" pn="section-toc.1-1.20.2.3.2.2.1"><xref derive
dContent="A.3.2" format="counter" sectionFormat="of" target="section-a.3.2"/>.  
<xref derivedContent="" format="title" sectionFormat="of" target="name-bandwidth
-allocation">Bandwidth Allocation</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.20.2.4">
<t indent="0" pn="section-toc.1-1.20.2.4.1"><xref derivedContent
="A.4" format="counter" sectionFormat="of" target="section-a.4"/>.  <xref derive
dContent="" format="title" sectionFormat="of" target="name-candidate-gathering">
Candidate Gathering</xref></t>
</li>
<li pn="section-toc.1-1.20.2.5">
<t indent="0" pn="section-toc.1-1.20.2.5.1"><xref derivedContent
="" format="none" sectionFormat="of" target="section-a.5"/><xref derivedContent=
"" format="title" sectionFormat="of" target="name-acknowledgements">Acknowledgem
ents</xref></t>
</li>
</ul>
</li>
<li pn="section-toc.1-1.21">
<t indent="0" pn="section-toc.1-1.21.1"><xref derivedContent="" form
at="none" sectionFormat="of" target="section-appendix.b"/><xref derivedContent="
" format="title" sectionFormat="of" target="name-authors-addresses">Authors' Add
resses</xref></t>
</li>
</ul>
</section>
</toc>
</front> </front>
<middle> <middle>
<section toc="include" numbered="true" removeInRFC="false" pn="section-1"> <section>
<name slugifiedName="name-introduction">Introduction</name> <name>Introduction</name>
<section toc="include" numbered="true" removeInRFC="false" pn="section-1.1 <section>
"> <name>Background</name>
<name slugifiedName="name-background">Background</name> <t>
<t indent="0" pn="section-1.1-1"> When the SDP offer/answer mechanism <xref target="RFC3264"/>
When the SDP offer/answer mechanism <xref format="default" target="RFC32
64" sectionFormat="of" derivedContent="RFC3264"/>
is used to negotiate the establishment of multimedia communication sessi ons, if separate is used to negotiate the establishment of multimedia communication sessi ons, if separate
transports (5-tuples) are negotiated for each individual media stream, e ach transport consumes transports (5-tuples) are negotiated for each individual media stream, e ach transport consumes
additional resources (especially when Interactive Connectivity Establish ment (ICE) additional resources (especially when Interactive Connectivity Establish ment (ICE)
<xref format="default" target="RFC8445" sectionFormat="of" derivedConten t="RFC8445"/> is used). <xref target="RFC8445"/> is used).
For this reason, it is attractive to use a single transport for multiple media streams. For this reason, it is attractive to use a single transport for multiple media streams.
</t> </t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-1.2 <section>
"> <name>BUNDLE Mechanism</name>
<name slugifiedName="name-bundle-mechanism">BUNDLE Mechanism</name> <t>
<t indent="0" pn="section-1.2-1">
This specification defines a way to use a single transport (BUNDLE trans port) This specification defines a way to use a single transport (BUNDLE trans port)
for sending and receiving media (bundled media) described by multiple SD P media descriptions for sending and receiving media (bundled media) described by multiple SD P media descriptions
("m=" sections). The address:port combination used by an endpoint for se nding and receiving ("m=" sections). The address:port combination used by an endpoint for se nding and receiving
bundled media is referred to as the BUNDLE address:port. The set of SDP bundled media is referred to as the "BUNDLE address:port". The set of SD
attributes that are P attributes that are
applied to each "m=" section within a BUNDLE group is referred to as BUN applied to each "m=" section within a BUNDLE group is referred to as "BU
DLE attributes. NDLE attributes".
The same BUNDLE transport is used for sending and receiving bundled medi a, which The same BUNDLE transport is used for sending and receiving bundled medi a, which
means that the symmetric Real-time Transport Protocol (RTP) mechanism <x ref format="default" target="RFC4961" sectionFormat="of" derivedContent="RFC4961 "/> is always used for RTP-based bundled media. means that the symmetric Real-time Transport Protocol (RTP) mechanism <x ref target="RFC4961"/> is always used for RTP-based bundled media.
</t> </t>
<t indent="0" pn="section-1.2-2"> <t>
This specification defines a new SDP Grouping Framework <xref format="de This specification defines a new SDP Grouping Framework <xref target="RF
fault" target="RFC5888" sectionFormat="of" derivedContent="RFC5888"/> extension C5888"/> extension called 'BUNDLE'. The extension can be used with the Session D
called 'BUNDLE'. The extension can be used with the Session Description escription
Protocol (SDP) offer/answer mechanism <xref format="default" target="RFC Protocol (SDP) offer/answer mechanism <xref target="RFC3264"/>
3264" sectionFormat="of" derivedContent="RFC3264"/>
to negotiate which "m=" sections will become part of a BUNDLE group. In addition, the offerer and to negotiate which "m=" sections will become part of a BUNDLE group. In addition, the offerer and
answerer <xref format="default" target="RFC3264" sectionFormat="of" deri vedContent="RFC3264"/> use the BUNDLE extension to negotiate answerer <xref target="RFC3264"/> use the BUNDLE extension to negotiate
the BUNDLE addresses:ports (offerer BUNDLE address:port and answerer BUN DLE address:port) and the the BUNDLE addresses:ports (offerer BUNDLE address:port and answerer BUN DLE address:port) and the
set of BUNDLE attributes (offerer BUNDLE attributes and answerer BUNDLE attributes) that will be applied to set of BUNDLE attributes (offerer BUNDLE attributes and answerer BUNDLE attributes) that will be applied to
each "m=" section within the BUNDLE group. each "m=" section within the BUNDLE group.
</t> </t>
<t indent="0" pn="section-1.2-3"> <t>
The use of a BUNDLE transport allows the usage of a single set of The use of a BUNDLE transport allows the usage of a single set of
ICE <xref format="default" target="RFC8445" sectionFormat="of" derivedCo ntent="RFC8445"/> candidates for the whole BUNDLE group. ICE candidates <xref target="RFC8445"/> for the whole BUNDLE group.
</t> </t>
<t indent="0" pn="section-1.2-4"> <t>
A given BUNDLE address:port <bcp14>MUST</bcp14> only be associated with a single BUNDLE group. If an SDP offer A given BUNDLE address:port <bcp14>MUST</bcp14> only be associated with a single BUNDLE group. If an SDP offer
or SDP answer (hereafter referred to as "offer" and "answer") contains m ultiple BUNDLE groups, the procedures in this specification apply to each or SDP answer (hereafter referred to as "offer" and "answer") contains m ultiple BUNDLE groups, the procedures in this specification apply to each
group independently. All RTP-based bundled media associated with a given BUNDLE group belong to a single group independently. All RTP-based bundled media associated with a given BUNDLE group belong to a single
RTP session <xref format="default" target="RFC3550" sectionFormat="of" d erivedContent="RFC3550"/>. RTP session <xref target="RFC3550"/>.
</t> </t>
<t indent="0" pn="section-1.2-5"> <t>
The BUNDLE extension is backward compatible. Endpoints that do not suppo rt the extension The BUNDLE extension is backward compatible. Endpoints that do not suppo rt the extension
are expected to generate offers and answers without an SDP 'group:BUNDLE ' attribute and are expected to generate offers and answers without an SDP 'group:BUNDLE ' attribute and
assign a unique address:port to each "m=" section within an offer and an swer, according assign a unique address:port to each "m=" section within an offer and an swer, according
to the procedures in to the procedures in
<xref format="default" target="RFC3264" sectionFormat="of" derivedContent ="RFC3264"/> and <xref format="default" target="RFC4566" sectionFormat="of" deri vedContent="RFC4566"/>. <xref target="RFC3264"/> and <xref target="RFC4566"/>.
</t> </t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-1.3 <section>
"> <name>Protocol Extensions</name>
<name slugifiedName="name-protocol-extensions">Protocol Extensions</name <t>
>
<t indent="0" pn="section-1.3-1">
In addition to defining the new SDP Grouping Framework extension, this s pecification defines In addition to defining the new SDP Grouping Framework extension, this s pecification defines
the following protocol extensions and RFC updates. This specification: the following protocol extensions and makes the following updates to RFC s. This specification:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
.3-2"> <li>
<li pn="section-1.3-2.1">
defines a new SDP attribute, 'bundle-only', which can be used to defines a new SDP attribute, 'bundle-only', which can be used to
request that a specific "m=" section (and the associated media) be use d only if kept request that a specific "m=" section (and the associated media) be use d only if kept
within a BUNDLE group. within a BUNDLE group.
</li> </li>
<li pn="section-1.3-2.2"> <li>
updates RFC 3264 <xref format="default" target="RFC3264" sectionFormat updates RFC 3264 <xref target="RFC3264"/> to also allow assigning a ze
="of" derivedContent="RFC3264"/>, to also allow assigning a zero port value to a ro port value to an "m=" section
n "m=" section
in cases where the media described by the "m=" section is not disabled or rejected. in cases where the media described by the "m=" section is not disabled or rejected.
</li> </li>
<li pn="section-1.3-2.3"> <li>
defines a new RTCP <xref format="default" target="RFC3550" sectionForm defines a new RTCP <xref target="RFC3550"/> SDES item, Media Identific
at="of" derivedContent="RFC3550"/> SDES item, 'MID', and a new RTP SDES header ation ('MID'), and a new RTP SDES header
extension that can be used to associate RTP streams with "m=" sections . extension that can be used to associate RTP streams with "m=" sections .
</li> </li>
<li pn="section-1.3-2.4"> <li>
updates <xref format="default" target="RFC7941" sectionFormat="of" der updates <xref target="RFC7941"/> by adding an exception,
ivedContent="RFC7941"/> by adding an exception,
for the MID RTP header extension, to the requirement regarding protect ion for the MID RTP header extension, to the requirement regarding protect ion
of an SDES RTP header extension carrying an SDES item for the MID RTP of an SDES RTP header extension carrying an SDES item for the MID RTP
header extension. header extension.
</li> </li>
<li pn="section-1.3-2.5"> <li>
updates <xref format="default" target="RFC5888" sectionFormat="of" der updates <xref target="RFC5888"/> by allowing an SDP 'group'
ivedContent="RFC5888"/> by allowing an SDP 'group'
attribute to contain an identification-tag that identifies an "m=" sec tion with the port value set to zero. attribute to contain an identification-tag that identifies an "m=" sec tion with the port value set to zero.
</li> </li>
</ul> </ul>
</section> </section>
<section anchor="sec-changes-8843" numbered="true" removeInRFC="false" toc <section anchor="sec-changes-8843">
="include" pn="section-1.4"> <name>Changes from RFC 8843</name>
<name slugifiedName="name-contradiction-regarding-bun">Changes from RFC
8843</name> <t>
<t indent="0" pn="section-1.4-1"> When <xref target="RFC8843"/> and <xref target="RFC8829"/>
When RFC 8843 and <xref format="default" target="RFC8829" sectionFormat="of" d were published, an inconsistency between the specifications was identified. Th
erivedContent="RFC8829"/> e procedures regarding assigning
were published an inconsistency between the specifications was identified. The
procedures regarding assigning
the port value to a bundled "m=" section in an answer (initial or subsequent) and a subsequent offer the port value to a bundled "m=" section in an answer (initial or subsequent) and a subsequent offer
were inconsistent. This specification removes the inconsistency by aligning th e port value assignment were inconsistent. This specification removes the inconsistency by aligning th e port value assignment
procedure with the procedure in RFC 8829. procedure with the procedure in <xref target="RFC8829"/>.
</t> </t>
<t indent="0" pn="section-1.4-2"> <t>
In addition, this document implements the following erratas: 6431, 6437 In addition, this document implements changes from the following errata report
s: <xref target="Err6431"/>, <xref target="Err6437"/>.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-term" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-term">
pn="section-2"> <name>Terminology</name>
<name slugifiedName="name-terminology">Terminology</name> <dl>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-2-1" <dt>"m=" section:</dt>
> <dd> SDP bodies contain one or more media descriptions, referred to
<li pn="section-2-1.1">
<dl newline="false" spacing="normal" indent="3" pn="section-2-1.1.1">
<dt pn="section-2-1.1.1.1">"m=" section:</dt>
<dd pn="section-2-1.1.1.2"> SDP bodies contain one or more media des
criptions, referred to
as "m=" sections. Each "m=" section is represented by an SDP "m=" line and zero or more as "m=" sections. Each "m=" section is represented by an SDP "m=" line and zero or more
SDP attributes associated with the "m=" line. A local address:port combina tion is SDP attributes associated with the "m=" line. A local address:port combina tion is
assigned to each "m=" section.</dd> assigned to each "m=" section.</dd>
<dt pn="section-2-1.1.1.3">5-tuple:</dt> <dt>5-tuple:</dt>
<dd pn="section-2-1.1.1.4">A collection of the following values: sou <dd>A collection of the following values: source address, source
rce address, source
port, destination address, destination port, and transport-layer port, destination address, destination port, and transport-layer
protocol.</dd> protocol.</dd>
<dt pn="section-2-1.1.1.5">Unique address:port:</dt> <dt>Unique address:port:</dt>
<dd pn="section-2-1.1.1.6">An address:port combination that is assig <dd>An address:port combination that is assigned to
ned to
only one "m=" section in an offer or answer.</dd> only one "m=" section in an offer or answer.</dd>
<dt pn="section-2-1.1.1.7">Offerer BUNDLE-tag:</dt> <dt>Offerer BUNDLE-tag:</dt>
<dd pn="section-2-1.1.1.8">The first identification-tag in a given <dd>The first identification-tag in a given
SDP 'group:BUNDLE' attribute identification-tag list in an offer.</dd> SDP 'group:BUNDLE' attribute identification-tag list in an offer.</dd>
<dt pn="section-2-1.1.1.9">Answerer BUNDLE-tag:</dt> <dt>Answerer BUNDLE-tag:</dt>
<dd pn="section-2-1.1.1.10">The first identification-tag in a given <dd>The first identification-tag in a given
SDP 'group:BUNDLE' attribute identification-tag list in an answer.</dd> SDP 'group:BUNDLE' attribute identification-tag list in an answer.</dd>
<dt pn="section-2-1.1.1.11"> Suggested offerer-tagged "m=" section:< <dt> Suggested offerer-tagged "m=" section:</dt>
/dt> <dd> The bundled "m=" section identified by the offerer BUNDLE-tag i
<dd pn="section-2-1.1.1.12"> The bundled "m=" section identified by n an initial BUNDLE offer,
the offerer BUNDLE-tag in an initial BUNDLE offer,
before a BUNDLE group has been negotiated.</dd> before a BUNDLE group has been negotiated.</dd>
<dt pn="section-2-1.1.1.13">Offerer-tagged "m=" section:</dt> <dt>Offerer-tagged "m=" section:</dt>
<dd pn="section-2-1.1.1.14">The bundled "m=" section identified by t <dd>The bundled "m=" section identified by the offerer BUNDLE-tag in
he offerer BUNDLE-tag in a subsequent offer. a subsequent offer.
The "m=" section contains characteristics (offerer BUNDLE address:port and offerer BUNDLE attributes) that are applied to The "m=" section contains characteristics (offerer BUNDLE address:port and offerer BUNDLE attributes) that are applied to
each "m=" section within the BUNDLE group.</dd> each "m=" section within the BUNDLE group.</dd>
<dt pn="section-2-1.1.1.15">Answerer-tagged "m=" section:</dt> <dt>Answerer-tagged "m=" section:</dt>
<dd pn="section-2-1.1.1.16">The bundled "m=" section identified by t <dd>The bundled "m=" section identified by the answerer BUNDLE-tag i
he answerer BUNDLE-tag in an answer n an answer
(initial BUNDLE answer or subsequent). The "m=" section contains character istics (answerer BUNDLE address:port and answerer BUNDLE attributes) (initial BUNDLE answer or subsequent). The "m=" section contains character istics (answerer BUNDLE address:port and answerer BUNDLE attributes)
that are applied to each "m=" section within the BUNDLE group.</dd> that are applied to each "m=" section within the BUNDLE group.</dd>
<dt pn="section-2-1.1.1.17">BUNDLE address:port:</dt> <dt>BUNDLE address:port:</dt>
<dd pn="section-2-1.1.1.18">An address:port combination that an endp <dd>An address:port combination that an endpoint uses for sending an
oint uses for sending and receiving d receiving
bundled media.</dd> bundled media.</dd>
<dt pn="section-2-1.1.1.19">Offerer BUNDLE address:port:</dt> <dt>Offerer BUNDLE address:port:</dt>
<dd pn="section-2-1.1.1.20">The address:port combination used by the <dd>The address:port combination used by the offerer
offerer
for sending and receiving media.</dd> for sending and receiving media.</dd>
<dt pn="section-2-1.1.1.21">Answerer BUNDLE address:port:</dt> <dt>Answerer BUNDLE address:port:</dt>
<dd pn="section-2-1.1.1.22">The address:port combination used by the <dd>The address:port combination used by the answerer
answerer
for sending and receiving media.</dd> for sending and receiving media.</dd>
<dt pn="section-2-1.1.1.23">BUNDLE attributes:</dt> <dt>BUNDLE attributes:</dt>
<dd pn="section-2-1.1.1.24"> IDENTICAL and TRANSPORT multiplexing ca <dd> IDENTICAL and TRANSPORT multiplexing category SDP
tegory SDP
attributes. Once a BUNDLE group has been created, the attribute values app ly attributes. Once a BUNDLE group has been created, the attribute values app ly
to each bundled "m=" section within the BUNDLE group.</dd> to each bundled "m=" section within the BUNDLE group.</dd>
<dt pn="section-2-1.1.1.25">Offerer BUNDLE attributes:</dt> <dt>Offerer BUNDLE attributes:</dt>
<dd pn="section-2-1.1.1.26">IDENTICAL and TRANSPORT multiplexing cat <dd>IDENTICAL and TRANSPORT multiplexing category SDP
egory SDP
attributes included in the offerer-tagged "m=" section. </dd> attributes included in the offerer-tagged "m=" section. </dd>
<dt pn="section-2-1.1.1.27">Answerer BUNDLE attributes:</dt> <dt>Answerer BUNDLE attributes:</dt>
<dd pn="section-2-1.1.1.28">IDENTICAL and TRANSPORT multiplexing cat <dd>IDENTICAL and TRANSPORT multiplexing category SDP
egory SDP
attributes included in the answerer-tagged "m=" section.</dd> attributes included in the answerer-tagged "m=" section.</dd>
<dt pn="section-2-1.1.1.29">BUNDLE transport:</dt> <dt>BUNDLE transport:</dt>
<dd pn="section-2-1.1.1.30">The transport (5-tuple) used by all medi <dd>The transport (5-tuple) used by all media described by the
a described by the
"m=" sections within a BUNDLE group.</dd> "m=" sections within a BUNDLE group.</dd>
<dt pn="section-2-1.1.1.31">BUNDLE group:</dt> <dt>BUNDLE group:</dt>
<dd pn="section-2-1.1.1.32">A set of bundled "m=" sections, created <dd>A set of bundled "m=" sections, created using an SDP offer/answe
using an SDP offer/answer r
exchange, that uses a single BUNDLE transport, and a single set of BUNDLE exchange, that uses a single BUNDLE transport and a single set of BUNDLE a
attributes, ttributes
for sending and receiving all media (bundled media) described by the set o f "m=" sections. for sending and receiving all media (bundled media) described by the set o f "m=" sections.
The same BUNDLE transport is used for sending and receiving bundled media. </dd> The same BUNDLE transport is used for sending and receiving bundled media. </dd>
<dt pn="section-2-1.1.1.33">Bundled "m=" section:</dt> <dt>Bundled "m=" section:</dt>
<dd pn="section-2-1.1.1.34">An "m=" section, whose identification-ta <dd>An "m=" section, whose identification-tag
g
is placed in an SDP 'group:BUNDLE' attribute identification-tag list is placed in an SDP 'group:BUNDLE' attribute identification-tag list
in an offer or answer.</dd> in an offer or answer.</dd>
<dt pn="section-2-1.1.1.35">Bundle-only "m=" section:</dt> <dt>Bundle-only "m=" section:</dt>
<dd pn="section-2-1.1.1.36">A bundled "m=" section that contains an <dd>A bundled "m=" section that contains an
SDP 'bundle-only' attribute.</dd> SDP 'bundle-only' attribute.</dd>
<dt pn="section-2-1.1.1.37">Bundled media:</dt> <dt>Bundled media:</dt>
<dd pn="section-2-1.1.1.38">All media associated with a given BUNDLE <dd>All media associated with a given BUNDLE group.</dd>
group.</dd> <dt>Initial BUNDLE offer:</dt>
<dt pn="section-2-1.1.1.39">Initial BUNDLE offer:</dt> <dd>The first offer, within an SDP session (e.g., a SIP dialog
<dd pn="section-2-1.1.1.40">The first offer, within an SDP session ( when SIP <xref target="RFC3261"/> is used to carry SDP), in which
e.g., a SIP dialog
when SIP <xref format="default" target="RFC3261" sectionFormat="of" derive
dContent="RFC3261"/> is used to carry SDP), in which
the offerer indicates that it wants to negotiate a given BUNDLE group.</dd > the offerer indicates that it wants to negotiate a given BUNDLE group.</dd >
<dt pn="section-2-1.1.1.41">Initial BUNDLE answer:</dt> <dt>Initial BUNDLE answer:</dt>
<dd pn="section-2-1.1.1.42">The answer to an initial BUNDLE offer in <dd>The answer to an initial BUNDLE offer in which the offerer indic
which the offerer indicates that it wants to negotiate ates that it wants to negotiate
a BUNDLE group, and the answerer accepts the creation of the BUNDLE group. The BUNDLE group is a BUNDLE group, and the answerer accepts the creation of the BUNDLE group. The BUNDLE group is
created once the answerer sends the initial BUNDLE answer.</dd> created once the answerer sends the initial BUNDLE answer.</dd>
<dt pn="section-2-1.1.1.43">Subsequent offer:</dt> <dt>Subsequent offer:</dt>
<dd pn="section-2-1.1.1.44">An offer that contains a BUNDLE group th <dd>An offer that contains a BUNDLE group that
at
has been created as part of a previous offer/answer exchange.</dd> has been created as part of a previous offer/answer exchange.</dd>
<dt pn="section-2-1.1.1.45">Subsequent answer:</dt> <dt>Subsequent answer:</dt>
<dd pn="section-2-1.1.1.46">An answer to a subsequent offer.</dd> <dd>An answer to a subsequent offer.</dd>
<dt pn="section-2-1.1.1.47">Identification-tag:</dt> <dt>Identification-tag:</dt>
<dd pn="section-2-1.1.1.48">A unique token value that is used to ide <dd>A unique token value that is used to identify an
ntify an "m=" section. The SDP 'mid' attribute <xref target="RFC5888"/> in an "m="
"m=" section. The SDP 'mid' attribute <xref format="default" target="RFC58 section carries the unique identification-tag
88" sectionFormat="of" derivedContent="RFC5888"/> in an "m=" section carries the
unique identification-tag
assigned to that "m=" section. The session-level SDP 'group' attribute assigned to that "m=" section. The session-level SDP 'group' attribute
<xref format="default" target="RFC5888" sectionFormat="of" derivedContent= "RFC5888"/> carries a list of <xref target="RFC5888"/> carries a list of
identification-tags, identifying the "m=" sections associated with that identification-tags, identifying the "m=" sections associated with that
particular 'group' attribute.</dd> particular 'group' attribute.</dd>
</dl> </dl>
</li>
</ul>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-3"> <section>
<name slugifiedName="name-conventions">Conventions</name> <name>Conventions</name>
<t indent="0" pn="section-3-1"> <t>
The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
"<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14> "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>
", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", ",
"<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
"<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
"<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
to be interpreted as described in BCP 14 <xref target="RFC2119" format="defa be
ult" sectionFormat="of" derivedContent="RFC2119"/> interpreted as described in BCP&nbsp;14 <xref target="RFC2119"/> <xref
<xref target="RFC8174" format="default" sectionFormat="of" derivedConten target="RFC8174"/> when, and only when, they appear in all capitals, as
t="RFC8174"/> when, and only when, they appear in all capitals, shown here.
as shown here. </t>
</t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-4"> <section>
<name slugifiedName="name-applicability-statement">Applicability Statement <name>Applicability Statement</name>
</name> <t>
<t indent="0" pn="section-4-1"> The mechanism in this specification only applies to SDP <xref target="RFC4
The mechanism in this specification only applies to SDP <xref format="defa 566"/>, when used together with the SDP offer/answer
ult" target="RFC4566" sectionFormat="of" derivedContent="RFC4566"/>, when used t mechanism <xref target="RFC3264"/>.
ogether with the SDP offer/answer
mechanism <xref format="default" target="RFC3264" sectionFormat="of" deriv
edContent="RFC3264"/>.
Declarative usage of SDP is out of scope of this document and is Declarative usage of SDP is out of scope of this document and is
thus undefined. thus undefined.
</t> </t>
</section> </section>
<section anchor="sec-group" toc="include" numbered="true" removeInRFC="false <section anchor="sec-group">
" pn="section-5"> <name>SDP Grouping Framework BUNDLE Extension</name>
<name slugifiedName="name-sdp-grouping-framework-bund">SDP Grouping Framew <t>
ork BUNDLE Extension</name> This section defines a new SDP Grouping Framework <xref target="RFC5888"/
<t indent="0" pn="section-5-1"> > extension, 'BUNDLE'. The BUNDLE extension can be used with the SDP
This section defines a new SDP Grouping Framework <xref format="default"
target="RFC5888" sectionFormat="of" derivedContent="RFC5888"/> extension, 'BUNDL
E'. The BUNDLE extension can be used with the SDP
offer/answer mechanism to negotiate a set of "m=" sections that will beco me part of a BUNDLE offer/answer mechanism to negotiate a set of "m=" sections that will beco me part of a BUNDLE
group. Within a BUNDLE group, each "m=" section uses a BUNDLE transport f or sending and group. Within a BUNDLE group, each "m=" section uses a BUNDLE transport f or sending and
receiving bundled media. Each endpoint uses a single address:port combina tion for sending and receiving bundled media. Each endpoint uses a single address:port combina tion for sending and
receiving the bundled media. receiving the bundled media.
</t> </t>
<t indent="0" pn="section-5-2"> <t>
The BUNDLE extension is indicated using an SDP 'group' attribute with a s emantics value The BUNDLE extension is indicated using an SDP 'group' attribute with a s emantics value
<xref format="default" target="RFC5888" sectionFormat="of" derivedContent ="RFC5888"/> of "BUNDLE". <xref target="RFC5888"/> of "BUNDLE".
An identification-tag is assigned to each bundled An identification-tag is assigned to each bundled
"m=" section, and each identification-tag is listed in the SDP 'group:BUN DLE' "m=" section, and each identification-tag is listed in the SDP 'group:BUN DLE'
attribute identification-tag list. Each "m=" section whose identification -tag attribute identification-tag list. Each "m=" section whose identification -tag
is listed in the identification-tag list is associated with a given is listed in the identification-tag list is associated with a given
BUNDLE group. BUNDLE group.
</t> </t>
<t indent="0" pn="section-5-3"> <t>
SDP bodies can contain multiple BUNDLE groups. Any given bundled "m=" SDP bodies can contain multiple BUNDLE groups. Any given bundled "m="
section <bcp14>MUST NOT</bcp14> be associated with more than one BUNDLE g roup at any given section <bcp14>MUST NOT</bcp14> be associated with more than one BUNDLE g roup at any given
time. time.
</t> </t>
<t indent="0" pn="section-5-4">
<t>
NOTE: The order of the "m=" sections listed in the SDP 'group:BUNDLE' att ribute NOTE: The order of the "m=" sections listed in the SDP 'group:BUNDLE' att ribute
identification-tag list does not have to be the same as the order in whic h identification-tag list does not have to be the same as the order in whic h
the "m=" sections occur in the SDP. the "m=" sections occur in the SDP.
</t> </t>
<t indent="0" pn="section-5-5"> <t>
The multiplexing category <xref target="RFC8859" format="default" section The multiplexing category <xref target="RFC8859"/> for the 'group:BUNDLE'
Format="of" derivedContent="RFC8859"/> for the 'group:BUNDLE'
attribute is 'NORMAL'. attribute is 'NORMAL'.
</t> </t>
<t indent="0" pn="section-5-6"> <t>
<xref target="sec-sdp-oa" format="default" sectionFormat="of" derivedCont <xref target="sec-sdp-oa"/> defines the
ent="Section 7"/> defines the
detailed SDP offer/answer procedures for the BUNDLE extension. detailed SDP offer/answer procedures for the BUNDLE extension.
</t> </t>
</section> </section>
<section anchor="sec-bundle-only" toc="include" numbered="true" removeInRFC= <section anchor="sec-bundle-only">
"false" pn="section-6"> <name>SDP 'bundle-only' Attribute</name>
<name slugifiedName="name-sdp-bundle-only-attribute">SDP 'bundle-only' Att <t>
ribute</name> This section defines a new SDP media-level attribute <xref target="RFC4566
<t indent="0" pn="section-6-1"> "/>, 'bundle-only'. 'bundle-only' is a property attribute
This section defines a new SDP media-level attribute <xref target="RFC4566 <xref target="RFC4566"/>; hence, it has no value.
" format="default" sectionFormat="of" derivedContent="RFC4566"/>, 'bundle-only'.
'bundle-only' is a property attribute
<xref target="RFC4566" format="default" sectionFormat="of" derivedContent=
"RFC4566"/> and hence has no value.
</t> </t>
<t indent="0" pn="section-6-2"> <t>
In order to ensure that an answerer that does not support the BUNDLE exten sion always In order to ensure that an answerer that does not support the BUNDLE exten sion always
rejects a bundled "m=" section in an offer, the offerer can assign a zero port value to the "m=" rejects a bundled "m=" section in an offer, the offerer can assign a zero port value to the "m="
section. According to <xref target="RFC3264" format="default" sectionForma t="of" derivedContent="RFC3264"/>, an answerer section. According to <xref target="RFC3264"/>, an answerer
will reject such an "m=" section. will reject such an "m=" section.
By including an SDP 'bundle-only' attribute in a bundled "m=" section, the offerer can By including an SDP 'bundle-only' attribute in a bundled "m=" section, the offerer can
request that the answerer accepts the "m=" section only if the answerer su pports the BUNDLE request that the answerer accept the "m=" section only if the answerer sup ports the BUNDLE
extension and if the answerer keeps the "m=" section within the associated BUNDLE group. extension and if the answerer keeps the "m=" section within the associated BUNDLE group.
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-6-3" <dl>
> <dt>Name:</dt>
<li pn="section-6-3.1"> <dd>bundle-only</dd>
<dl newline="false" spacing="normal" indent="3" pn="section-6-3.1.1"> <dt>Value:</dt>
<dt pn="section-6-3.1.1.1">Name:</dt> <dd>N/A</dd>
<dd pn="section-6-3.1.1.2">bundle-only</dd> <dt>Usage Level:</dt>
<dt pn="section-6-3.1.1.3">Value:</dt> <dd>media</dd>
<dd pn="section-6-3.1.1.4">N/A</dd> <dt>Charset Dependent:</dt>
<dt pn="section-6-3.1.1.5">Usage Level:</dt> <dd>no</dd>
<dd pn="section-6-3.1.1.6">media</dd> <dt>Example:</dt>
<dt pn="section-6-3.1.1.7">Charset Dependent:</dt> <dd>a=bundle-only</dd>
<dd pn="section-6-3.1.1.8">no</dd>
<dt pn="section-6-3.1.1.9">Example:</dt>
<dd pn="section-6-3.1.1.10">a=bundle-only</dd>
</dl> </dl>
</li> <t>
</ul>
<t indent="0" pn="section-6-5">
The usage of the 'bundle-only' attribute is only defined for a The usage of the 'bundle-only' attribute is only defined for a
bundled "m=" section with a zero port value. Other usage is bundled "m=" section with a zero port value. Other usage is
unspecified. If an offerer or answerer receives a ‘bundle-only’ unspecified. If an offerer or answerer receives a 'bundle-only'
attribute in a non-bundled "m=" section the offerer or answerer attribute in a non-bundled "m=" section, the offerer or answerer
MUST discard the attribute. <bcp14>MUST</bcp14> discard the attribute.
</t> </t>
<t indent="0" pn="section-6-6"> <t>
<xref target="sec-sdp-oa" format="default" sectionFormat="of" derivedConte <xref target="sec-sdp-oa"/> defines the detailed SDP
nt="Section 7"/> defines the detailed SDP
offer/answer procedures for the 'bundle-only' attribute. offer/answer procedures for the 'bundle-only' attribute.
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa" toc="include" numbered="true" removeInRFC="fals <section anchor="sec-sdp-oa">
e" pn="section-7"> <name>SDP Offer/Answer Procedures</name>
<name slugifiedName="name-sdp-offer-answer-procedures">SDP Offer/Answer Pr <t>
ocedures</name> This section describes the SDP offer/answer <xref target="RFC3264"/> pro
<t indent="0" pn="section-7-1"> cedures for:
This section describes the SDP offer/answer <xref format="default" targe
t="RFC3264" sectionFormat="of" derivedContent="RFC3264"/> procedures for:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7-2 <ul>
"> <li>
<li pn="section-7-2.1">
Negotiating a BUNDLE group; Negotiating a BUNDLE group;
</li> </li>
<li pn="section-7-2.2"> <li>
Suggesting and selecting the tagged "m=" sections (offerer-tagged "m =" section and answerer-tagged "m=" section); Suggesting and selecting the tagged "m=" sections (offerer-tagged "m =" section and answerer-tagged "m=" section);
</li> </li>
<li pn="section-7-2.3"> <li>
Adding an "m=" section to a BUNDLE group; Adding an "m=" section to a BUNDLE group;
</li> </li>
<li pn="section-7-2.4"> <li>
Moving an "m=" section out of a BUNDLE group; and Moving an "m=" section out of a BUNDLE group; and
</li> </li>
<li pn="section-7-2.5"> <li>
Disabling an "m=" section within a BUNDLE group. Disabling an "m=" section within a BUNDLE group.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7-3"> <t>
The generic rules and procedures defined in <xref format="default" targe The generic rules and procedures defined in <xref target="RFC3264"/> and
t="RFC3264" sectionFormat="of" derivedContent="RFC3264"/> and <xref format="defa <xref target="RFC5888"/>
ult" target="RFC5888" sectionFormat="of" derivedContent="RFC5888"/>
also apply to the BUNDLE extension. For example, if an offer is rejected also apply to the BUNDLE extension. For example, if an offer is rejected
by the answerer, the previously negotiated addresses:ports, SDP paramete rs, and characteristics by the answerer, the previously negotiated addresses:ports, SDP paramete rs, and characteristics
(including those associated with a BUNDLE group) apply. Hence, if an off erer (including those associated with a BUNDLE group) apply. Hence, if an off erer
generates an offer in order to negotiate a BUNDLE group, generates an offer in order to negotiate a BUNDLE group
and the answerer rejects the offer, the BUNDLE group is not created. and the answerer rejects the offer, the BUNDLE group is not created.
</t> </t>
<t indent="0" pn="section-7-4"> <t>
The procedures in this section are independent of the media type or The procedures in this section are independent of the media type or
"m=" line proto value assigned to a bundled "m=" section. <xref format=" default" target="sec-bundle-only" sectionFormat="of" derivedContent="Section 6"/ > defines "m=" line proto value assigned to a bundled "m=" section. <xref target=" sec-bundle-only"/> defines
additional considerations for the usage of the SDP 'bundle-only' attribu te. additional considerations for the usage of the SDP 'bundle-only' attribu te.
<xref format="default" target="sec-rtp" sectionFormat="of" derivedConten t="Section 9"/> defines additional <xref target="sec-rtp"/> defines additional
considerations for RTP-based media. considerations for RTP-based media.
<xref format="default" target="sec-ice" sectionFormat="of" derivedConten <xref target="sec-ice"/> defines additional
t="Section 10"/> defines additional considerations for the usage of the ICE mechanism
considerations for the usage of the ICE <xref target="RFC8445"/>.
<xref format="default" target="RFC8445" sectionFormat="of" derivedConten
t="RFC8445"/> mechanism.
</t> </t>
<t indent="0" pn="section-7-5"> <t>
Offers and answers can contain multiple BUNDLE groups. The procedures in this Offers and answers can contain multiple BUNDLE groups. The procedures in this
section apply independently to a given BUNDLE group. section apply independently to a given BUNDLE group.
</t> </t>
<section anchor="sec-sdp-cons" toc="include" numbered="true" removeInRFC=" <section anchor="sec-sdp-cons">
false" pn="section-7.1"> <name>Generic SDP Considerations</name>
<name slugifiedName="name-generic-sdp-considerations">Generic SDP Consid <t>
erations</name>
<t indent="0" pn="section-7.1-1">
This section describes generic restrictions associated with the usage of This section describes generic restrictions associated with the usage of
SDP parameters within a BUNDLE group. It also describes how to calcula te a SDP parameters within a BUNDLE group. It also describes how to calcula te a
value for the whole BUNDLE group, when parameter and attribute values have been assigned value for the whole BUNDLE group, when parameter and attribute values have been assigned
to each bundled "m=" section. to each bundled "m=" section.
</t> </t>
<section anchor="sec-sdp-cons-c" toc="include" numbered="true" removeInR <section anchor="sec-sdp-cons-c">
FC="false" pn="section-7.1.1"> <name>Connection Data ("c=")</name>
<name slugifiedName="name-connection-data-c">Connection Data ("c=")</n <t>
ame> The "c=" line nettype value <xref target="RFC4566"/> associated with
<t indent="0" pn="section-7.1.1-1"> a bundled "m=" section <bcp14>MUST</bcp14> be 'IN'.
The "c=" line nettype value <xref format="default" target="RFC4566"
sectionFormat="of" derivedContent="RFC4566"/> associated with a bundled "m=" sec
tion <bcp14>MUST</bcp14> be 'IN'.
</t> </t>
<t indent="0" pn="section-7.1.1-2"> <t>
The "c=" line addrtype value <xref format="default" target="RFC4566" The "c=" line addrtype value <xref target="RFC4566"/> associated wit
sectionFormat="of" derivedContent="RFC4566"/> associated with a bundled "m=" se h a bundled "m=" section <bcp14>MUST</bcp14> be 'IP4' or
ction <bcp14>MUST</bcp14> be 'IP4' or
'IP6'. The same value <bcp14>MUST</bcp14> be associated with each "m =" section. 'IP6'. The same value <bcp14>MUST</bcp14> be associated with each "m =" section.
</t> </t>
<t indent="0" pn="section-7.1.1-3">
<t indent="3">
NOTE: Extensions to this specification can specify usage of the BUND LE NOTE: Extensions to this specification can specify usage of the BUND LE
mechanism for other nettype and addrtype values than the ones listed above. mechanism for other nettype and addrtype values than the ones listed above.
</t> </t>
</section> </section>
<section anchor="sec-sdp-cons-b" toc="include" numbered="true" removeInR <section anchor="sec-sdp-cons-b">
FC="false" pn="section-7.1.2"> <name>Bandwidth ("b=")</name>
<name slugifiedName="name-bandwidth-b">Bandwidth ("b=")</name> <t>
<t indent="0" pn="section-7.1.2-1">
An offerer and answerer <bcp14>MUST</bcp14> use the rules and restri ctions defined An offerer and answerer <bcp14>MUST</bcp14> use the rules and restri ctions defined
in <xref target="RFC8859" format="default" sectionFormat="of" derive dContent="RFC8859"/> for in <xref target="RFC8859"/> for
associating the SDP bandwidth ("b=") line with bundled "m=" sections . associating the SDP bandwidth ("b=") line with bundled "m=" sections .
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-cat" toc="include" numbered="true" removeInR <section anchor="sec-sdp-oa-cat">
FC="false" pn="section-7.1.3"> <name>Attributes ("a=")</name>
<name slugifiedName="name-attributes-a">Attributes ("a=")</name> <t>
<t indent="0" pn="section-7.1.3-1">
An offerer and answerer <bcp14>MUST</bcp14> include SDP attributes i n every bundled "m=" section where applicable, An offerer and answerer <bcp14>MUST</bcp14> include SDP attributes i n every bundled "m=" section where applicable,
following the normal offer/answer procedures for each attribute, wit h the following exceptions: following the normal offer/answer procedures for each attribute, wit h the following exceptions:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.1.3-2"> <li>
<li pn="section-7.1.3-2.1">
In the initial BUNDLE offer, the offerer <bcp14>MUST NOT</bcp14> In the initial BUNDLE offer, the offerer <bcp14>MUST NOT</bcp14>
include IDENTICAL and TRANSPORT multiplexing category SDP include IDENTICAL and TRANSPORT multiplexing category SDP
attributes (BUNDLE attributes) in bundle-only "m=" sections. The attributes (BUNDLE attributes) in bundle-only "m=" sections. The
offerer <bcp14>MUST</bcp14> include such attributes in all other offerer <bcp14>MUST</bcp14> include such attributes in all other
bundled "m=" sections. In the initial BUNDLE offer, each bundled bundled "m=" sections. In the initial BUNDLE offer, each bundled
"m=" line can contain a different set of BUNDLE attributes and "m=" line can contain a different set of BUNDLE attributes and
attribute values. Once the offerer-tagged "m=" section has been attribute values. Once the offerer-tagged "m=" section has been
selected, the BUNDLE attributes contained in the offerer-tagged selected, the BUNDLE attributes contained in the offerer-tagged
"m=" section will apply to each bundled "m=" section within the "m=" section will apply to each bundled "m=" section within the
BUNDLE group. BUNDLE group.
</li> </li>
<li pn="section-7.1.3-2.2"> <li>
In a subsequent offer, or in an answer (initial or subsequent), In a subsequent offer or in an answer (initial or subsequent),
the offerer and answerer <bcp14>MUST</bcp14> include IDENTICAL the offerer and answerer <bcp14>MUST</bcp14> include IDENTICAL
and TRANSPORT multiplexing category SDP attributes (BUNDLE and TRANSPORT multiplexing category SDP attributes (BUNDLE
attributes) only in the tagged "m=" section (offerer-tagged "m=" attributes) only in the tagged "m=" section (offerer-tagged "m="
section or answerer-tagged "m=" section). The offerer and section or answerer-tagged "m=" section). The offerer and
answerer <bcp14>MUST NOT</bcp14> include such attributes in any answerer <bcp14>MUST NOT</bcp14> include such attributes in any
other bundled "m=" section. The BUNDLE attributes contained in other bundled "m=" section. The BUNDLE attributes contained in
the tagged "m=" section will apply to each bundled "m=" section the tagged "m=" section will apply to each bundled "m=" section
within the BUNDLE group. within the BUNDLE group.
</li> </li>
<li pn="section-7.1.3-2.3"> <li>
In an offer (initial BUNDLE offer or subsequent), or in an In an offer (initial BUNDLE offer or subsequent) or in an
answer (initial BUNDLE answer or subsequent), the offerer and answer (initial BUNDLE answer or subsequent), the offerer and
answerer <bcp14>MUST</bcp14> include SDP attributes from answerer <bcp14>MUST</bcp14> include SDP attributes from
categories other than IDENTICAL and TRANSPORT in each bundled categories other than IDENTICAL and TRANSPORT in each bundled
"m=" section that a given attribute applies to. Each bundled "m=" section that a given attribute applies to. Each bundled
"m=" line can contain a different set of such attributes, and "m=" line can contain a different set of such attributes and
attribute values, as such attributes only apply to the given attribute values, as such attributes only apply to the given
bundled "m=" section in which they are included. bundled "m=" section in which they are included.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.1.3-3"> <t indent="3">
NOTE: A consequence of the rules above is that media-specific NOTE: A consequence of the rules above is that media-specific
IDENTICAL and TRANSPORT multiplexing category SDP attributes that IDENTICAL and TRANSPORT multiplexing category SDP attributes that
are applicable only to some of the bundled "m=" sections within are applicable only to some of the bundled "m=" sections within
the BUNDLE group might appear in the tagged "m=" section for which the BUNDLE group might appear in the tagged "m=" section for which
they are not applicable. For instance, the tagged "m=" section they are not applicable. For instance, the tagged "m=" section
might contain an SDP 'rtcp-mux' attribute even if the tagged "m=" might contain an SDP 'rtcp-mux' attribute even if the tagged "m="
section does not describe RTP-based media (but another bundled section does not describe RTP-based media (but another bundled
"m=" section within the BUNDLE group does describe RTP-based "m=" section within the BUNDLE group does describe RTP-based
media). media).
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-sdp-oa-ino" toc="include" numbered="true" removeInRFC <section anchor="sec-sdp-oa-ino">
="false" pn="section-7.2"> <name>Generating the Initial BUNDLE Offer</name>
<name slugifiedName="name-generating-the-initial-bundle-">Generating the <t>
Initial BUNDLE offer</name> The procedures in this section apply to the first offer within an SDP
<t indent="0" pn="section-7.2-1"> session (e.g., a SIP
The procedures in this section apply to the first offer, within an SDP dialog when SIP <xref target="RFC3261"/> is used to carry SDP) in whic
session (e.g., a SIP h the
dialog when SIP <xref target="RFC3261" format="default" sectionFormat=
"of" derivedContent="RFC3261"/> is used to carry SDP), in which the
offerer indicates that it wants to negotiate a given BUNDLE group. Thi s could occur in the offerer indicates that it wants to negotiate a given BUNDLE group. Thi s could occur in the
initial offer, or in a subsequent offer, of the SDP session. initial offer, or in a subsequent offer, of the SDP session.
</t> </t>
<t indent="0" pn="section-7.2-2"> <t>
When an offerer generates an initial BUNDLE offer, in order to negotia te a When an offerer generates an initial BUNDLE offer, in order to negotia te a
BUNDLE group, it <bcp14>MUST</bcp14>: BUNDLE group, it <bcp14>MUST</bcp14>:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.2-3"> <li>
<li pn="section-7.2-3.1"> Assign a unique address:port to each bundled "m=" section
Assign a unique address:port to each bundled "m=" section, following the procedures in <xref target="RFC3264"/>, excluding an
following the procedures in <xref target="RFC3264" format="default y bundle-only "m=" sections (see below);
" sectionFormat="of" derivedContent="RFC3264"/>, excluding any bundle-only "m="
sections (see below);
</li> </li>
<li pn="section-7.2-3.2"> <li>
Pick a bundled "m=" section as the suggested offerer-tagged "m=" ( Pick a bundled "m=" section as the suggested offerer-tagged "m=" (
<xref target="sec-sdp-oa-ino-req" format="default" sectionFormat="of" derivedCon <xref target="sec-sdp-oa-ino-req"/>);
tent="Section 7.2.1"/>);
</li> </li>
<li pn="section-7.2-3.3"> <li>
Include SDP attributes in the bundled "m=" sections following the rules Include SDP attributes in the bundled "m=" sections following the rules
in <xref target="sec-sdp-oa-cat" format="default" sectionFormat="o f" derivedContent="Section 7.1.3"/>; in <xref target="sec-sdp-oa-cat"/>;
</li> </li>
<li pn="section-7.2-3.4"> <li>
Include an SDP 'group:BUNDLE' attribute in the offer; and Include an SDP 'group:BUNDLE' attribute in the offer; and
</li> </li>
<li pn="section-7.2-3.5"> <li>
Place the identification-tag of each bundled "m=" section in the Place the identification-tag of each bundled "m=" section in the
SDP 'group:BUNDLE' attribute identification-tag list. The offerer BUNDLE-tag SDP 'group:BUNDLE' attribute identification-tag list. The offerer BUNDLE-tag
indicates the suggested offerer-tagged "m=" section. indicates the suggested offerer-tagged "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.2-4"> <t indent="3">
NOTE: When the offerer assigns unique addresses:ports to multiple bund led "m=" sections, the offerer needs to be prepared NOTE: When the offerer assigns unique addresses:ports to multiple bund led "m=" sections, the offerer needs to be prepared
to receive bundled media on each unique address:port, until it receive s the associated answer and finds out which to receive bundled media on each unique address:port until it receives the associated answer and finds out which
bundled "m=" section (and associated address:port combination) the ans werer has selected as the offerer-tagged "m=" section. bundled "m=" section (and associated address:port combination) the ans werer has selected as the offerer-tagged "m=" section.
</t> </t>
<t indent="0" pn="section-7.2-5"> <t>
If the offerer wants to request that the answerer accepts a given bund If the offerer wants to request that the answerer accept a given bundl
led "m=" section only if ed "m=" section only if
the answerer keeps the "m=" section within the negotiated BUNDLE group , the offerer <bcp14>MUST</bcp14>: the answerer keeps the "m=" section within the negotiated BUNDLE group , the offerer <bcp14>MUST</bcp14>:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.2-6"> <li>
<li pn="section-7.2-6.1"> Include an SDP 'bundle-only' attribute (<xref target="sec-sdp-oa-i
Include an SDP 'bundle-only' attribute (<xref target="sec-sdp-oa-i no-req"/>) in the "m=" section, and
no-req" format="default" sectionFormat="of" derivedContent="Section 7.2.1"/>) in
the "m=" section, and
</li> </li>
<li pn="section-7.2-6.2"> <li>
Assign a zero port value to the "m=" section. Assign a zero port value to the "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.2-7"> <t indent="3">
NOTE: If the offerer assigns a zero port value to a bundled "m=" secti NOTE: If the offerer assigns a zero port value to a bundled "m=" secti
on, but does not include an on but does not include an
SDP 'bundle-only' attribute in the "m=" section, it is an indication t hat the offerer wants SDP 'bundle-only' attribute in the "m=" section, it is an indication t hat the offerer wants
to disable the "m=" section (<xref target="sec-sdp-oa-mod-dis" format= "default" sectionFormat="of" derivedContent="Section 7.5.3"/>). to disable the "m=" section (<xref target="sec-sdp-oa-mod-dis"/>).
</t> </t>
<t indent="0" pn="section-7.2-8"> <t>
Sections <xref target="sec-sdp-oa-ino-ex" format="counter" sectionForm Sections <xref target="sec-sdp-oa-ino-ex" format="counter"/> and <xref
at="of" derivedContent="7.2.2"/> and <xref target="sec-example-add" format="coun target="sec-example-add" format="counter"/> show
ter" sectionFormat="of" derivedContent="18.1"/> show
an example of an initial BUNDLE offer. an example of an initial BUNDLE offer.
</t> </t>
<section anchor="sec-sdp-oa-ino-req" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-ino-req">
eInRFC="false" pn="section-7.2.1"> <name>Suggesting the Offerer-Tagged "m=" Section</name>
<name slugifiedName="name-suggesting-the-offerer-tagg">Suggesting the <t>
Offerer-Tagged 'm=' Section</name>
<t indent="0" pn="section-7.2.1-1">
In the initial BUNDLE offer, the bundled "m=" section indicated by the offerer BUNDLE-tag is the suggested offerer-tagged "m=" section. In the initial BUNDLE offer, the bundled "m=" section indicated by the offerer BUNDLE-tag is the suggested offerer-tagged "m=" section.
The address:port combination associated with the "m=" section will be used by the offerer for sending and receiving bundled The address:port combination associated with the "m=" section will be used by the offerer for sending and receiving bundled
media if the answerer selects the "m=" section as the offerer-tagged " m=" section (<xref target="sec-sdp-oa-ans-off" format="default" sectionFormat="o f" derivedContent="Section 7.3.1"/>). In addition, if the answerer selects the " m=" section as the offerer-tagged "m=" section, media if the answerer selects the "m=" section as the offerer-tagged " m=" section (<xref target="sec-sdp-oa-ans-off"/>). In addition, if the answerer selects the "m=" section as the offerer-tagged "m=" section,
the BUNDLE attributes included in the "m=" section will be applied to each "m=" section within the negotiated BUNDLE group. the BUNDLE attributes included in the "m=" section will be applied to each "m=" section within the negotiated BUNDLE group.
</t> </t>
<t indent="0" pn="section-7.2.1-2"> <t>
The offerer <bcp14>MUST NOT</bcp14> suggest a bundle-only "m=" section as the offerer-tagged "m=" section. The offerer <bcp14>MUST NOT</bcp14> suggest a bundle-only "m=" section as the offerer-tagged "m=" section.
</t> </t>
<t indent="0" pn="section-7.2.1-3"> <t>
It is <bcp14>RECOMMENDED</bcp14> that the suggested offerer-tagged "m= " section be a bundled "m=" section It is <bcp14>RECOMMENDED</bcp14> that the suggested offerer-tagged "m= " section be a bundled "m=" section
that the offerer believes is unlikely that the answerer will reject or which the offerer believes is unlikely to be rejected or moved out of
move out of the BUNDLE group. the BUNDLE group by the answerer.
How such assumption is made is outside the scope of this document. How such an assumption is made is outside the scope of this document.
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-ino-ex" numbered="true" toc="include" remove <section anchor="sec-sdp-oa-ino-ex">
InRFC="false" pn="section-7.2.2"> <name>Example: Initial BUNDLE Offer</name>
<name slugifiedName="name-example-initial-bundle-offer">Example: Initi <t>
al BUNDLE offer</name>
<t indent="0" pn="section-7.2.2-1">
The following example shows an initial BUNDLE offer. The offer include s two The following example shows an initial BUNDLE offer. The offer include s two
"m=" sections in the offer and suggests that both "m=" sections are in cluded in a BUNDLE group. "m=" sections in the offer and suggests that both "m=" sections be inc luded in a BUNDLE group.
The audio "m=" section is the suggested offerer-tagged "m=" section, i ndicated by placing the The audio "m=" section is the suggested offerer-tagged "m=" section, i ndicated by placing the
identification-tag associated with the "m=" section (offerer BUNDLE-ta g) first in the SDP group:BUNDLE identification-tag associated with the "m=" section (offerer BUNDLE-ta g) first in the SDP 'group:BUNDLE'
attribute identification-id list. attribute identification-id list.
</t> </t>
<t keepWithNext="true" indent="0" pn="section-7.2.2-2">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-7.2.2-3"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 940 skipping to change at line 617
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 10002 RTP/AVP 31 32 m=video 10002 RTP/AVP 31 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtcp-mux a=rtcp-mux
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
<t indent="0" pn="section-7.2.2-4"> <t>
The following example shows an initial BUNDLE offer. The offer include s two The following example shows an initial BUNDLE offer. The offer include s two
"m=" sections in the offer and suggests that both "m=" sections are in cluded in a BUNDLE group. "m=" sections in the offer and suggests that both "m=" sections are in cluded in a BUNDLE group.
The offerer includes an SDP 'bundle-only' attribute in the video "m=" The offerer includes an SDP 'bundle-only' attribute in the video "m="
section, to request that the section to request that the
answerer accepts the "m=" section only if the answerer supports the BU answerer accept the "m=" section only if the answerer supports the BUN
NDLE extension and if the DLE extension and if the
answerer keeps the "m=" section within the associated BUNDLE group. answerer keeps the "m=" section within the associated BUNDLE group.
The audio "m=" section is the suggested offerer-tagged "m=" section, i ndicated by placing the The audio "m=" section is the suggested offerer-tagged "m=" section, i ndicated by placing the
identification-tag associated with the "m=" section (offerer BUNDLE-ta g) first in the SDP group:BUNDLE identification-tag associated with the "m=" section (offerer BUNDLE-ta g) first in the SDP 'group:BUNDLE'
attribute identification-id list. attribute identification-id list.
</t> </t>
<t keepWithNext="true" indent="0" pn="section-7.2.2-5">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-7.2.2-6"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 978 skipping to change at line 656
m=video 0 RTP/AVP 31 32 m=video 0 RTP/AVP 31 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=bundle-only a=bundle-only
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
</section> </section>
<section anchor="sec-sdp-oa-ans" toc="include" numbered="true" removeInRFC <section anchor="sec-sdp-oa-ans">
="false" pn="section-7.3"> <name>Generating the SDP Answer</name>
<name slugifiedName="name-generating-the-sdp-answer">Generating the SDP <t>
Answer</name>
<t indent="0" pn="section-7.3-1">
When an answerer generates an answer (initial BUNDLE answer or subsequ ent) that contains a BUNDLE group, the following general When an answerer generates an answer (initial BUNDLE answer or subsequ ent) that contains a BUNDLE group, the following general
SDP Grouping Framework restrictions, defined in <xref target="RFC5888" format="default" sectionFormat="of" derivedContent="RFC5888"/>, also apply to t he BUNDLE group: SDP Grouping Framework restrictions, defined in <xref target="RFC5888" />, also apply to the BUNDLE group:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.3-2"> <li>
<li pn="section-7.3-2.1">
The answerer is only allowed to include a BUNDLE group in an The answerer is only allowed to include a BUNDLE group in an
initial BUNDLE answer if the offerer requested the BUNDLE group initial BUNDLE answer if the offerer requested the BUNDLE group
to be created in the corresponding initial BUNDLE offer; to be created in the corresponding initial BUNDLE offer;
</li> </li>
<li pn="section-7.3-2.2"> <li>
The answerer is only allowed to include a BUNDLE group in a The answerer is only allowed to include a BUNDLE group in a
subsequent answer if the corresponding subsequent offer contains subsequent answer if the corresponding subsequent offer contains
a previously negotiated BUNDLE group; a previously negotiated BUNDLE group;
</li> </li>
<li pn="section-7.3-2.3"> <li>
The answerer is only allowed to include a bundled "m=" section The answerer is only allowed to include a bundled "m=" section
in an answer if the "m=" section was indicated as bundled in the in an answer if the "m=" section was indicated as bundled in the
corresponding offer; and corresponding offer; and
</li> </li>
<li pn="section-7.3-2.4"> <li>
The answerer is only allowed to include a bundled "m=" section The answerer is only allowed to include a bundled "m=" section
in the same BUNDLE group as the bundled "m=" line in the in the same BUNDLE group as the bundled "m=" line in the
corresponding offer. corresponding offer.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3-3"> <t>
In addition, when an answerer generates an answer (initial BUNDLE In addition, when an answerer generates an answer (initial BUNDLE
answer or subsequent) that contains a BUNDLE group, the answerer answer or subsequent) that contains a BUNDLE group, the answerer
<bcp14>MUST</bcp14>: <bcp14>MUST</bcp14>:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.3-4"> <li>
<li pn="section-7.3-4.1">
In case of an initial BUNDLE answer, select the offerer-tagged In case of an initial BUNDLE answer, select the offerer-tagged
"m=" section using the procedures in <xref target="sec-sdp-oa-ans- off" format="default" sectionFormat="of" derivedContent="Section 7.3.1"/>. In ca se of a "m=" section using the procedures in <xref target="sec-sdp-oa-ans- off"/>. In case of a
subsequent answer, the offerer-tagged "m=" section is indicated subsequent answer, the offerer-tagged "m=" section is indicated
in the corresponding subsequent offer and <bcp14>MUST NOT</bcp14> be changed by the answerer; in the corresponding subsequent offer and <bcp14>MUST NOT</bcp14> be changed by the answerer;
</li> </li>
<li pn="section-7.3-4.2"> <li>
Select the answerer-tagged "m=" section (<xref target="sec-sdp-oa- Select the answerer-tagged "m=" section (<xref target="sec-sdp-oa-
ans-off" format="default" sectionFormat="of" derivedContent="Section 7.3.1"/>); ans-off"/>);
</li> </li>
<li pn="section-7.3-4.3"> <li>
Assign the answerer BUNDLE address:port to the answerer-tagged Assign the answerer BUNDLE address:port to the answerer-tagged
"m=" section, and to every other bundled "m=" section within the BU NDLE "m=" section and to every other bundled "m=" section within the BUN DLE
group; group;
</li> </li>
<li pn="section-7.3-4.5"> <li>
Include SDP attributes in the bundled "m=" sections following the rules Include SDP attributes in the bundled "m=" sections following the rules
in <xref target="sec-sdp-oa-cat" format="default" sectionFormat="o f" derivedContent="Section 7.1.3"/>; in <xref target="sec-sdp-oa-cat"/>;
</li> </li>
<li pn="section-7.3-4.6"> <li>
Include an SDP 'group:BUNDLE' attribute in the answer; and Include an SDP 'group:BUNDLE' attribute in the answer; and
</li> </li>
<li pn="section-7.3-4.7"> <li>
Place the identification-tag of each bundled "m=" section in the Place the identification-tag of each bundled "m=" section in the
SDP 'group:BUNDLE' attribute identification-tag list. The answerer BUNDLE-tag SDP 'group:BUNDLE' attribute identification-tag list. The answerer BUNDLE-tag
indicates the answerer-tagged "m=" section (<xref target="sec-sdp- oa-ans-off" format="default" sectionFormat="of" derivedContent="Section 7.3.1"/> ). indicates the answerer-tagged "m=" section (<xref target="sec-sdp- oa-ans-off"/>).
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3-5"> <t>
If the answerer does not want to keep an "m=" section within a BUNDLE group, it <bcp14>MUST</bcp14>: If the answerer does not want to keep an "m=" section within a BUNDLE group, it <bcp14>MUST</bcp14>:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.3-6"> <li>
<li pn="section-7.3-6.1"> Move the "m=" section out of the BUNDLE group (<xref target="sec-s
Move the "m=" section out of the BUNDLE group (<xref target="sec-s dp-oa-ans-mov"/>); or
dp-oa-ans-mov" format="default" sectionFormat="of" derivedContent="Section 7.3.2
"/>); or
</li> </li>
<li pn="section-7.3-6.2"> <li>
Reject the "m=" section (<xref target="sec-sdp-oa-ans-rej" format= Reject the "m=" section (<xref target="sec-sdp-oa-ans-rej"/>).
"default" sectionFormat="of" derivedContent="Section 7.3.3"/>).
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3-7"> <t>
The answerer can modify the answerer BUNDLE address:port, add and remo ve SDP attributes, or modify The answerer can modify the answerer BUNDLE address:port, add and remo ve SDP attributes, or modify
SDP attribute values in a subsequent answer. Changes to the answerer B UNDLE address:port SDP attribute values in a subsequent answer. Changes to the answerer B UNDLE address:port
and the answerer BUNDLE attributes will be applied to each bundled "m= " section within the BUNDLE group. and the answerer BUNDLE attributes will be applied to each bundled "m= " section within the BUNDLE group.
</t> </t>
<t indent="0" pn="section-7.3-8"> <t indent="3">
NOTE: If a bundled "m=" section in an offer contains a zero port value , but the "m=" section NOTE: If a bundled "m=" section in an offer contains a zero port value , but the "m=" section
does not contain an SDP 'bundle-only' attribute, it is an indication t hat the offerer wants does not contain an SDP 'bundle-only' attribute, it is an indication t hat the offerer wants
to disable the "m=" section (<xref target="sec-sdp-oa-mod-dis" format= "default" sectionFormat="of" derivedContent="Section 7.5.3"/>). to disable the "m=" section (<xref target="sec-sdp-oa-mod-dis"/>).
</t> </t>
<section anchor="sec-sdp-oa-ans-off" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-ans-off">
eInRFC="false" pn="section-7.3.1"> <name>Answerer Selection of Tagged "m=" Sections</name>
<name slugifiedName="name-answerer-selection-of-tagge">Answerer Select <t>
ion of Tagged 'm=' Sections</name>
<t indent="0" pn="section-7.3.1-1">
When selecting the offerer-tagged "m=" section, the answerer <bcp14>MU ST</bcp14> When selecting the offerer-tagged "m=" section, the answerer <bcp14>MU ST</bcp14>
first check whether the "m=" section fulfills the following criteria first check whether the "m=" section fulfills the following criteria
<xref target="sec-sdp-oa-ino-req" format="default" sectionFormat="of" derivedContent="Section 7.2.1"/>: (<xref target="sec-sdp-oa-ino-req"/>):
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.3.1-2"> <li>
<li pn="section-7.3.1-2.1">
The answerer will not move the "m=" section out of the BUNDLE grou p The answerer will not move the "m=" section out of the BUNDLE grou p
(<xref target="sec-sdp-oa-ans-mov" format="default" sectionFormat= "of" derivedContent="Section 7.3.2"/>); (<xref target="sec-sdp-oa-ans-mov"/>);
</li> </li>
<li pn="section-7.3.1-2.2"> <li>
The answerer will not reject the "m=" section (<xref target="sec-s The answerer will not reject the "m=" section (<xref target="sec-s
dp-oa-ans-rej" format="default" sectionFormat="of" derivedContent="Section 7.3.3 dp-oa-ans-rej"/>); and
"/>); and
</li> </li>
<li pn="section-7.3.1-2.3"> <li>
The "m=" section does not contain a zero port value. The "m=" section does not contain a zero port value.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3.1-3"> <t>
If all of the criteria above are fulfilled, the answerer <bcp14>MUST</ bcp14> select If all of the criteria above are fulfilled, the answerer <bcp14>MUST</ bcp14> select
the "m=" section as the offerer-tagged "m=" section and <bcp14>MUST</b cp14> also mark the "m=" section as the offerer-tagged "m=" section and <bcp14>MUST</b cp14> also mark
the corresponding "m=" section in the answer as the answerer-tagged "m =" section. the corresponding "m=" section in the answer as the answerer-tagged "m =" section.
In the answer, the answerer BUNDLE-tag indicates the answerer-tagged " m=" section. In the answer, the answerer BUNDLE-tag indicates the answerer-tagged " m=" section.
</t> </t>
<t indent="0" pn="section-7.3.1-4"> <t>
If one or more of the criteria are not fulfilled, the answerer <bcp14> MUST</bcp14> pick the next If one or more of the criteria are not fulfilled, the answerer <bcp14> MUST</bcp14> pick the next
identification-tag in the identification-tag list in the offer and per form the same criteria identification-tag in the identification-tag list in the offer and per form the same criteria
check for the "m=" section indicated by that identification-tag. If th ere are no check for the "m=" section indicated by that identification-tag. If th ere are no
more identification-tags in the identification-tag list, the answerer <bcp14>MUST NOT</bcp14> more identification-tags in the identification-tag list, the answerer <bcp14>MUST NOT</bcp14>
create the BUNDLE group. In addition, unless the answerer rejects the whole offer, create the BUNDLE group. In addition, unless the answerer rejects the whole offer,
the answerer <bcp14>MUST</bcp14> apply the answerer procedures for mov ing an "m=" section out of a the answerer <bcp14>MUST</bcp14> apply the answerer procedures for mov ing an "m=" section out of a
BUNDLE group (<xref target="sec-sdp-oa-ans-mov" format="default" secti BUNDLE group (<xref target="sec-sdp-oa-ans-mov"/>) or
onFormat="of" derivedContent="Section 7.3.2"/>) or rejecting an "m=" section within a BUNDLE group (<xref target="sec-sdp
rejecting an "m=" section within a BUNDLE group (<xref target="sec-sdp -oa-ans-rej"/>) to every bundled "m=" section in the offer when
-oa-ans-rej" format="default" sectionFormat="of" derivedContent="Section 7.3.3"/
>) to every bundled "m=" section in the offer when
creating the answer. creating the answer.
</t> </t>
<t indent="0" pn="section-7.3.1-5"> <t>
<xref target="sec-example-add" format="default" sectionFormat="of" der <xref target="sec-example-add"/> shows an
ivedContent="Section 18.1"/> shows an
example of an offerer BUNDLE address:port selection. example of an offerer BUNDLE address:port selection.
</t> </t>
<t indent="0" pn="section-7.3.1-6"> <t>
Sections <xref target="sec-sdp-oa-ans-ex" format="counter" sectionForm Sections <xref target="sec-sdp-oa-ans-ex" format="counter"/> and
at="of" derivedContent="7.3.4"/> and <xref target="sec-example-add" format="counter"/> show an example of a
<xref target="sec-example-add" format="counter" sectionFormat="of" der n
ivedContent="18.1"/> show an example of an
answerer-tagged "m=" section selection. answerer-tagged "m=" section selection.
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-ans-mov" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-ans-mov">
eInRFC="false" pn="section-7.3.2"> <name>Moving a Media Description Out of a BUNDLE Group</name>
<name slugifiedName="name-moving-a-media-description-">Moving a Media <t>
Description Out of a BUNDLE Group</name> When an answerer generates the answer, the answerer <bcp14>MUST</bcp14
<t indent="0" pn="section-7.3.2-1"> > first check the following criteria if it wants to move a bundled "m=" section
When an answerer generates the answer, if the answerer wants to move a out of
bundled "m=" section out of the negotiated BUNDLE group:
the negotiated BUNDLE group, the answerer <bcp14>MUST</bcp14> first ch
eck the following criteria:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.3.2-2"> <li>
<li pn="section-7.3.2-2.1">
In the corresponding offer, the "m=" section is within a previousl y negotiated BUNDLE group, and In the corresponding offer, the "m=" section is within a previousl y negotiated BUNDLE group, and
</li> </li>
<li pn="section-7.3.2-2.2"> <li>
In the corresponding offer, the "m=" section contains an SDP 'bund le-only' attribute. In the corresponding offer, the "m=" section contains an SDP 'bund le-only' attribute.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3.2-3"> <t>
If either criterion above is fulfilled, the answerer cannot move the " m=" section out of If either criterion above is fulfilled, the answerer cannot move the " m=" section out of
the BUNDLE group in the answer. The answerer can reject the whole offe r, reject each the BUNDLE group in the answer. The answerer can reject the whole offe r, reject each
bundled "m=" section within the BUNDLE group (<xref target="sec-sdp-oa -ans-rej" format="default" sectionFormat="of" derivedContent="Section 7.3.3"/>), bundled "m=" section within the BUNDLE group (<xref target="sec-sdp-oa -ans-rej"/>),
or keep the "m=" section within the BUNDLE group in the answer and lat er create an offer where or keep the "m=" section within the BUNDLE group in the answer and lat er create an offer where
the "m=" section is moved out of the BUNDLE group (<xref target="sec-s dp-oa-mod-mov" format="default" sectionFormat="of" derivedContent="Section 7.5.2 "/>). the "m=" section is moved out of the BUNDLE group (<xref target="sec-s dp-oa-mod-mov"/>).
</t> </t>
<t indent="0" pn="section-7.3.2-4"> <t indent="3">
NOTE: One consequence of the rules above is that, once a BUNDLE group has been negotiated, a bundled "m=" section NOTE: One consequence of the rules above is that, once a BUNDLE group has been negotiated, a bundled "m=" section
cannot be moved out of the BUNDLE group in an answer. Instead, an offe r is needed. cannot be moved out of the BUNDLE group in an answer. Instead, an offe r is needed.
</t> </t>
<t indent="0" pn="section-7.3.2-5"> <t>
When the answerer generates an answer, in which it moves a bundled "m= When the answerer generates an answer in which it moves a bundled "m="
" section out section out
of a BUNDLE group, the answerer: of a BUNDLE group, the answerer:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.3.2-6"> <li>
<li pn="section-7.3.2-6.1">
<bcp14>MUST</bcp14> assign a unique address:port to the "m=" secti on; <bcp14>MUST</bcp14> assign a unique address:port to the "m=" secti on;
</li> </li>
<li pn="section-7.3.2-6.2"> <li>
<bcp14>MUST</bcp14> include any applicable SDP attribute in the "m <bcp14>MUST</bcp14> include any applicable SDP attribute in the "m
=" section, using the normal =" section using the normal
offer/answer procedures for each attribute; offer/answer procedures for each attribute;
</li> </li>
<li pn="section-7.3.2-6.3"> <li>
<bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in <bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in
the SDP 'group:BUNDLE' attribute identification-tag list associated with the SDP 'group:BUNDLE' attribute identification-tag list associated with
the BUNDLE group; and the BUNDLE group; and
</li> </li>
<li pn="section-7.3.2-6.4"> <li>
<bcp14>MUST NOT</bcp14> include an SDP 'bundle-only' attribute to the "m=" section. <bcp14>MUST NOT</bcp14> include an SDP 'bundle-only' attribute to the "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3.2-7"> <t>
Because an answerer is not allowed to move an "m=" section from one BU NDLE group to another within an answer Because an answerer is not allowed to move an "m=" section from one BU NDLE group to another within an answer
(<xref target="sec-sdp-oa-ans" format="default" sectionFormat="of" der ivedContent="Section 7.3"/>), if (<xref target="sec-sdp-oa-ans"/>), if
the answerer wants to move an "m=" section from one BUNDLE group to an other, it <bcp14>MUST</bcp14> first move the the answerer wants to move an "m=" section from one BUNDLE group to an other, it <bcp14>MUST</bcp14> first move the
"m=" section out of the current BUNDLE group and then generate an offe r where the "m=" section is "m=" section out of the current BUNDLE group and then generate an offe r where the "m=" section is
added to another BUNDLE group (<xref target="sec-sdp-oa-mod-add" forma t="default" sectionFormat="of" derivedContent="Section 7.5.1"/>). added to another BUNDLE group (<xref target="sec-sdp-oa-mod-add"/>).
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-ans-rej" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-ans-rej">
eInRFC="false" pn="section-7.3.3"> <name>Rejecting a Media Description in a BUNDLE Group</name>
<name slugifiedName="name-rejecting-a-media-descripti">Rejecting a Med <t>
ia Description in a BUNDLE Group</name>
<t indent="0" pn="section-7.3.3-1">
When an answerer wants to reject a bundled "m=" section in an answer, it <bcp14>MUST</bcp14> first check When an answerer wants to reject a bundled "m=" section in an answer, it <bcp14>MUST</bcp14> first check
the following criterion: the following criterion:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.3.3-2"> <li>
<li pn="section-7.3.3-2.1">
In the corresponding offer (subsequent), the "m=" section is the off erer-tagged "m=" section. In the corresponding offer (subsequent), the "m=" section is the off erer-tagged "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.3.3-3"> <t>
If the criterion above is fulfilled, the answerer cannot reject the "m =" section in If the criterion above is fulfilled, the answerer cannot reject the "m =" section in
the answer. The answerer can reject the whole offer, reject each bundl ed "m=" section the answer. The answerer can reject the whole offer, reject each bundl ed "m=" section
within the BUNDLE group, or keep the "m=" section within the BUNDLE gr oup in the answer and later create within the BUNDLE group, or keep the "m=" section within the BUNDLE gr oup in the answer and later create
an offer where the "m=" section is disabled within the BUNDLE group (< xref target="sec-sdp-oa-mod-dis" format="default" sectionFormat="of" derivedCont ent="Section 7.5.3"/>). an offer where the "m=" section is disabled within the BUNDLE group (< xref target="sec-sdp-oa-mod-dis"/>).
</t> </t>
<t indent="0" pn="section-7.3.3-4"> <t>
When an answerer generates an answer, in which it rejects a bundled "m When an answerer generates an answer in which it rejects a bundled "m=
=" section, " section,
the answerer: the answerer:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.3.3-5"> <li>
<li pn="section-7.3.3-5.1">
<bcp14>MUST</bcp14> assign a zero port value to the "m=" section, according to the procedures in <bcp14>MUST</bcp14> assign a zero port value to the "m=" section, according to the procedures in
<xref target="RFC3264" format="default" sectionFormat="of" derivedCo ntent="RFC3264"/>; <xref target="RFC3264"/>;
</li> </li>
<li pn="section-7.3.3-5.2"> <li>
<bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in <bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in
the SDP 'group:BUNDLE' attribute identification-tag list associated with the SDP 'group:BUNDLE' attribute identification-tag list associated with
the BUNDLE group; and the BUNDLE group; and
</li> </li>
<li pn="section-7.3.3-5.3"> <li>
<bcp14>MUST NOT</bcp14> include an SDP 'bundle-only' attribute in the "m=" section. <bcp14>MUST NOT</bcp14> include an SDP 'bundle-only' attribute in the "m=" section.
</li> </li>
</ul> </ul>
</section> </section>
<section anchor="sec-sdp-oa-ans-ex" numbered="true" toc="include" remove <section anchor="sec-sdp-oa-ans-ex">
InRFC="false" pn="section-7.3.4"> <name>Example: SDP Answer</name>
<name slugifiedName="name-example-sdp-answer">Example: SDP Answer</nam <t>
e> The example below shows an answer based on the corresponding offer in
<t indent="0" pn="section-7.3.4-1"> <xref target="sec-sdp-oa-ino-ex"/>.
The example below shows an answer, based on the corresponding offer in
<xref target="sec-sdp-oa-ino-ex" format="default" sectionFormat="of" d
erivedContent="Section 7.2.2"/>.
The answerer accepts both bundled "m=" sections within the created The answerer accepts both bundled "m=" sections within the created
BUNDLE group. The audio "m=" section is the answerer-tagged "m=" secti on, indicated BUNDLE group. The audio "m=" section is the answerer-tagged "m=" secti on, indicated
by placing the identification-tag associated with the "m=" section by placing the identification-tag associated with the "m=" section
(answerer BUNDLE-tag) first in the SDP group;BUNDLE attribute (answerer BUNDLE-tag) first in the SDP 'group:BUNDLE' attribute
identification-id list. identification-id list.
</t> </t>
<t keepWithNext="true" indent="0" pn="section-7.3.4-2">SDP Answer</t> <t keepWithNext="true">SDP Answer</t>
<sourcecode type="sdp" markers="false" pn="section-7.3.4-3"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 1230 skipping to change at line 908
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 20000 RTP/AVP 32 m=video 20000 RTP/AVP 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
<section anchor="sec-sdp-oa-ans-8843" numbered="true" toc="include" remo <section anchor="sec-sdp-oa-ans-8843">
veInRFC="false" pn="section-7.3.5"> <name>RFC 8843 Considerations</name>
<name slugifiedName="name-example-sdp-answer-8843">RFC 8843 Considerat <t>
ions</name> In <xref target="RFC8843"/>, instead of assigning the offerer BUNDLE
<t indent="0" pn="section-7.3.5-1"> address:port to
In RFC 8843, instead of assigning the offerer BUNDLE address:port to
each "m=" section within the BUNDLE group when modifying the session each "m=" section within the BUNDLE group when modifying the session
(<xref target="name-modifying-the-session" format="default" sectionF (<xref target="sec-sdp-oa-mod"/>), the offerer only assigned the off
ormat="of" erer BUNDLE
derivedContent="Section 7.5"/>), the offerer only assigned the offer
er BUNDLE
address:port to the offerer-tagged "m=" section. For every other "m =" section address:port to the offerer-tagged "m=" section. For every other "m =" section
within the BUNDLE group, the offerer included an SDP 'bundle-only' a ttribute in, within the BUNDLE group, the offerer included an SDP 'bundle-only' a ttribute in,
and assigned a zero port value to, the "m=" section. The way an answ erer compliant and assigned a zero port value to, the "m=" section. The way an answ erer compliant
to this specification processes such offer is considered an implemen with this specification processes such offer is considered an implem
tation issue entation issue
(e.g., based on whether the answerer needs to be backward compatible (e.g., based on whether the answerer needs to be backward compatible
with RFC 8843 with offerers compliant with <xref target="RFC8843"/>) and is outside the scope
compliant offerers), and is outside the scope of this specification. of this specification. The example below
The example below shows such an SDP Offer:
shows such SDP offer:
</t> </t>
<t keepWithNext="true" indent="0" pn="section-7.3.5-2">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-7.3.5-3"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 1273 skipping to change at line 949
m=video 0 RTP/AVP 31 32 m=video 0 RTP/AVP 31 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=bundle-only a=bundle-only
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
</section> </section>
<section anchor="sec-sdp-oa-off-ans" toc="include" numbered="true" removeI <section anchor="sec-sdp-oa-off-ans">
nRFC="false" pn="section-7.4"> <name>Offerer Processing of the SDP Answer</name>
<name slugifiedName="name-offerer-processing-of-the-s">Offerer Processin <t>
g of the SDP Answer</name>
<t indent="0" pn="section-7.4-1">
When an offerer receives an answer, if the answer contains a BUNDLE grou p, the offerer When an offerer receives an answer, if the answer contains a BUNDLE grou p, the offerer
<bcp14>MUST</bcp14> check that any bundled "m=" section in the answer wa s indicated as bundled in the <bcp14>MUST</bcp14> check that any bundled "m=" section in the answer wa s indicated as bundled in the
corresponding offer (for the same BUNDLE group). If there is no mismatch , the offerer <bcp14>MUST</bcp14> apply the properties (BUNDLE address:port, corresponding offer (for the same BUNDLE group). If there is no mismatch , the offerer <bcp14>MUST</bcp14> apply the properties (BUNDLE address:port,
BUNDLE attributes, etc.) of the offerer-tagged "m=" section (selected by the answerer; see BUNDLE attributes, etc.) of the offerer-tagged "m=" section (selected by the answerer; see
<xref format="default" target="sec-sdp-oa-ans-off" sectionFormat="of" de rivedContent="Section 7.3.1"/>) to each bundled "m=" section <xref target="sec-sdp-oa-ans-off"/>) to each bundled "m=" section
within the BUNDLE group. within the BUNDLE group.
</t> </t>
<t indent="0" pn="section-7.4-2"> <t indent="3">
NOTE: As the answerer might reject one or more bundled "m=" sections in NOTE: As the answerer might reject one or more bundled "m=" sections in
an initial BUNDLE offer, an initial BUNDLE offer
or move a bundled "m=" section out of a BUNDLE group, a given bundled "m =" section in the or move a bundled "m=" section out of a BUNDLE group, a given bundled "m =" section in the
offer might not be indicated as bundled in the corresponding answer. offer might not be indicated as bundled in the corresponding answer.
</t> </t>
<t indent="0" pn="section-7.4-3"> <t>
If the answer does not contain a BUNDLE group, the offerer <bcp14>MUST</ bcp14> process the answer If the answer does not contain a BUNDLE group, the offerer <bcp14>MUST</ bcp14> process the answer
as a normal answer. as a normal answer.
</t> </t>
<section anchor="sec-sdp-oa-off-8843" numbered="true" toc="include" remo <section anchor="sec-sdp-oa-off-8843">
veInRFC="false" pn="section-7.4.1"> <name>RFC 8843 Considerations</name>
<name slugifiedName="name-example-sdp-offer-8843">RFC 8843 Considerati <t>
ons</name> In <xref target="RFC8843"/>, instead of assigning the answerer BUNDL
<t indent="0" pn="section-7.4.1-1"> E address:port to
In RFC 8843, instead of assigning the answerer BUNDLE address:port t
o
each "m=" section within the BUNDLE group when generating the each "m=" section within the BUNDLE group when generating the
SDP answer(<xref target="sec-sdp-oa-ans" format="default" SDP Answer (<xref target="sec-sdp-oa-ans"/>), the answerer only assi
sectionFormat="of" derivedContent="Section 7.3"/>), the answerer onl gned the
y assigned the
answerer BUNDLE address:port to the answerer-tagged "m=" section. answerer BUNDLE address:port to the answerer-tagged "m=" section.
For every other "m=" section within the BUNDLE group, the answerer For every other "m=" section within the BUNDLE group, the answerer
included an SDP 'bundle-only' attribute in, and assigned a zero port included an SDP 'bundle-only' attribute in, and assigned a zero port
value to, the "m=" section. The way an offerer compliant value to, the "m=" section. The way an offerer compliant
to this specification processes such SDP answer is considered an imp with this specification processes such an SDP Answer is considered a
lementation issue n implementation issue
(e.g., based on whether the answerer needs to be backward compatible (e.g., based on whether the answerer needs to be backward compatible
with RFC 8843 with offerers compliant with <xref target="RFC8843"/>) and is outside the scope
compliant offerers), and is outside the scope of this specification. of this specification. The example below
The example below shows such an SDP Answer:
shows such SDP answer:
</t> </t>
<t keepWithNext="true" indent="0" pn="section-7.4.1-2">SDP Answer</t> <t keepWithNext="true">SDP Answer</t>
<sourcecode type="sdp" markers="false" pn="section-7.4.1-3"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 1333 skipping to change at line 1007
m=video 0 RTP/AVP 32 m=video 0 RTP/AVP 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=bundle-only a=bundle-only
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
</section> </section>
<section anchor="sec-sdp-oa-mod" toc="include" numbered="true" removeInRFC <section anchor="sec-sdp-oa-mod">
="false" pn="section-7.5"> <name>Modifying the Session</name>
<name slugifiedName="name-modifying-the-session">Modifying the Session</ <t>
name> When a BUNDLE group has been previously negotiated and an offerer gene
<t indent="0" pn="section-7.5-1"> rates a subsequent
When a BUNDLE group has been previously negotiated, and an offerer gen
erates a subsequent
offer, the offerer <bcp14>MUST</bcp14>: offer, the offerer <bcp14>MUST</bcp14>:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.5-2"> <li>
<li pn="section-7.5-2.1">
Pick one bundled "m=" section as the offerer-tagged "m=" section. The offerer Pick one bundled "m=" section as the offerer-tagged "m=" section. The offerer
can pick either the "m=" section that was previously selected by t he answerer can pick either the "m=" section that was previously selected by t he answerer
as the offerer-tagged "m=" section or another bundled "m=" section within the as the offerer-tagged "m=" section or another bundled "m=" section within the
BUNDLE group; BUNDLE group;
</li> </li>
<li pn="section-7.5-2.2"> <li>
Assign a BUNDLE address:port (previously negotiated or newly Assign a BUNDLE address:port (previously negotiated or newly
suggested) to the offerer-tagged "m=" section, and to every other suggested) to the offerer-tagged "m=" section and to every other
bundled "m=" section within the BUNDLE group; bundled "m=" section within the BUNDLE group;
</li> </li>
<li pn="section-7.5-2.4"> <li>
Include SDP attributes in the bundled "m=" sections following the rules in Include SDP attributes in the bundled "m=" sections following the rules in
<xref target="sec-sdp-oa-cat" format="default" sectionFormat="of" derivedContent="Section 7.1.3"/>; <xref target="sec-sdp-oa-cat"/>;
</li> </li>
<li pn="section-7.5-2.5"> <li>
Include an SDP 'group:BUNDLE' attribute in the offer; and Include an SDP 'group:BUNDLE' attribute in the offer; and
</li> </li>
<li pn="section-7.5-2.6"> <li>
Place the identification-tag of each bundled "m=" section in the Place the identification-tag of each bundled "m=" section in the
SDP 'group:BUNDLE' attribute identification-tag list. The offerer BUNDLE-tag SDP 'group:BUNDLE' attribute identification-tag list. The offerer BUNDLE-tag
indicates the offerer-tagged "m=" section. indicates the offerer-tagged "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.5-3"> <t>
The offerer <bcp14>MUST NOT</bcp14> pick a given bundled "m=" section as the offerer-tagged "m=" section if: The offerer <bcp14>MUST NOT</bcp14> pick a given bundled "m=" section as the offerer-tagged "m=" section if:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-7 <ul>
.5-4"> <li>
<li pn="section-7.5-4.1">
The offerer wants to move the "m=" section out of the BUNDLE group The offerer wants to move the "m=" section out of the BUNDLE group
(<xref target="sec-sdp-oa-mod-mov" format="default" sectionFormat= "of" derivedContent="Section 7.5.2"/>), or (<xref target="sec-sdp-oa-mod-mov"/>), or
</li> </li>
<li pn="section-7.5-4.2"> <li>
The offerer wants to disable the "m=" section (<xref format="defau The offerer wants to disable the "m=" section (<xref target="sec-s
lt" target="sec-sdp-oa-mod-dis" sectionFormat="of" derivedContent="Section 7.5.3 dp-oa-mod-dis"/>).
"/>).
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.5-5"> <t>
The offerer can modify the offerer BUNDLE address:port, add and remove SDP attributes, or modify The offerer can modify the offerer BUNDLE address:port, add and remove SDP attributes, or modify
SDP attribute values in the subsequent offer. Changes to the offerer B UNDLE address:port and the SDP attribute values in the subsequent offer. Changes to the offerer B UNDLE address:port and the
offerer BUNDLE attributes will (if the offer is accepted by the answer er) be applied to each offerer BUNDLE attributes will (if the offer is accepted by the answer er) be applied to each
bundled "m=" section within the BUNDLE group. bundled "m=" section within the BUNDLE group.
</t> </t>
<section anchor="sec-sdp-oa-mod-add" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-mod-add">
eInRFC="false" pn="section-7.5.1"> <name>Adding a Media Description to a BUNDLE Group</name>
<name slugifiedName="name-adding-a-media-description-">Adding a Media <t>
Description to a BUNDLE Group</name> When an offerer generates a subsequent offer in which it wants to add
<t indent="0" pn="section-7.5.1-1"> a bundled "m=" section to
When an offerer generates a subsequent offer, in which it wants to add a previously negotiated BUNDLE group, the offerer follows the procedur
a bundled "m=" section to es in <xref target="sec-sdp-oa-mod"/>. The offerer picks either the added "m=" s
a previously negotiated BUNDLE group, the offerer follows the procedur ection or an "m=" section
es in <xref target="sec-sdp-oa-mod" format="default" sectionFormat="of" derivedC
ontent="Section 7.5"/>. The offerer picks either the added "m=" section or an "m
=" section
previously added to the BUNDLE group as the offerer-tagged "m=" sectio n. previously added to the BUNDLE group as the offerer-tagged "m=" sectio n.
</t> </t>
<t indent="0" pn="section-7.5.1-2"> <t indent="3">
NOTE: As described in <xref target="sec-sdp-oa-ans-mov" format="defaul NOTE: As described in <xref target="sec-sdp-oa-ans-mov"/>, the answere
t" sectionFormat="of" derivedContent="Section 7.3.2"/>, the answerer cannot move r cannot move the added "m=" section
the added "m=" section
out of the BUNDLE group in its answer. If the answerer wants to move t he "m=" section out of the BUNDLE group, it will have to first accept out of the BUNDLE group in its answer. If the answerer wants to move t he "m=" section out of the BUNDLE group, it will have to first accept
it into the BUNDLE group in the answer, and then send a subsequent off it into the BUNDLE group in the answer and then send a subsequent offe
er where the "m=" section is moved out of the BUNDLE group r where the "m=" section is moved out of the BUNDLE group
(<xref target="sec-sdp-oa-mod-mov" format="default" sectionFormat="of" (<xref target="sec-sdp-oa-mod-mov"/>).
derivedContent="Section 7.5.2"/>).
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-mod-mov" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-mod-mov">
eInRFC="false" pn="section-7.5.2"> <name>Moving a Media Description Out of a BUNDLE Group</name>
<name slugifiedName="name-moving-a-media-description-o">Moving a Media <t>
Description Out of a BUNDLE Group</name> When an offerer generates a subsequent offer in which it wants to remo
<t indent="0" pn="section-7.5.2-1"> ve a bundled "m=" section from
When an offerer generates a subsequent offer, in which it wants to rem
ove a bundled "m=" section from
a BUNDLE group, the offerer: a BUNDLE group, the offerer:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.5.2-2"> <li>
<li pn="section-7.5.2-2.1">
<bcp14>MUST</bcp14> assign a unique address:port to the "m=" secti on; <bcp14>MUST</bcp14> assign a unique address:port to the "m=" secti on;
</li> </li>
<li pn="section-7.5.2-2.2"> <li>
<bcp14>MUST</bcp14> include SDP attributes in the "m=" section fol lowing the <bcp14>MUST</bcp14> include SDP attributes in the "m=" section fol lowing the
normal offer/answer rules for each attribute; normal offer/answer rules for each attribute;
</li> </li>
<li pn="section-7.5.2-2.3"> <li>
<bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in <bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in
the SDP 'group:BUNDLE' attribute identification-tag list associated with the SDP 'group:BUNDLE' attribute identification-tag list associated with
the BUNDLE group; and the BUNDLE group; and
</li> </li>
<li pn="section-7.5.2-2.4"> <li>
<bcp14>MUST NOT</bcp14> assign an SDP 'bundle-only' attribute to t he "m=" section. <bcp14>MUST NOT</bcp14> assign an SDP 'bundle-only' attribute to t he "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.5.2-3"> <t>
For the other bundled "m=" sections within the BUNDLE group, the offer er follows the procedures For the other bundled "m=" sections within the BUNDLE group, the offer er follows the procedures
in <xref target="sec-sdp-oa-mod" format="default" sectionFormat="of" d erivedContent="Section 7.5"/>. in <xref target="sec-sdp-oa-mod"/>.
</t> </t>
<t indent="0" pn="section-7.5.2-4"> <t>
An offerer <bcp14>MUST NOT</bcp14> move an "m=" section from one BUNDL E group to another within a An offerer <bcp14>MUST NOT</bcp14> move an "m=" section from one BUNDL E group to another within a
single offer. If the offerer wants to move an "m=" section from one BU NDLE group to single offer. If the offerer wants to move an "m=" section from one BU NDLE group to
another, it <bcp14>MUST</bcp14> first move the BUNDLE group out of the current BUNDLE group, and then another, it <bcp14>MUST</bcp14> first move the BUNDLE group out of the current BUNDLE group and then
generate a second offer where the "m=" section is added to another BUN DLE group generate a second offer where the "m=" section is added to another BUN DLE group
(<xref target="sec-sdp-oa-mod-add" format="default" sectionFormat="of" derivedContent="Section 7.5.1"/>). (<xref target="sec-sdp-oa-mod-add"/>).
</t> </t>
<t indent="0" pn="section-7.5.2-5"> <t>
<xref target="sec-example-off-mov" format="default" sectionFormat="of" <xref target="sec-example-off-mov"/>
derivedContent="Section 18.4"/>
shows an example of an offer for moving an "m=" section out of a BUNDL E group. shows an example of an offer for moving an "m=" section out of a BUNDL E group.
</t> </t>
</section> </section>
<section anchor="sec-sdp-oa-mod-dis" toc="include" numbered="true" remov <section anchor="sec-sdp-oa-mod-dis">
eInRFC="false" pn="section-7.5.3"> <name>Disabling a Media Description in a BUNDLE Group</name>
<name slugifiedName="name-disabling-a-media-descripti">Disabling a Med <t>
ia Description in a BUNDLE Group</name> When an offerer generates a subsequent offer in which it wants to disa
<t indent="0" pn="section-7.5.3-1"> ble a bundled "m=" section from
When an offerer generates a subsequent offer, in which it wants to dis
able a bundled "m=" section from
a BUNDLE group, the offerer: a BUNDLE group, the offerer:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section <ul>
-7.5.3-2"> <li>
<li pn="section-7.5.3-2.1">
<bcp14>MUST</bcp14> assign a zero port value to the "m=" section, following the procedures <bcp14>MUST</bcp14> assign a zero port value to the "m=" section, following the procedures
in <xref target="RFC4566" format="default" sectionFormat="of" derive dContent="RFC4566"/>; in <xref target="RFC4566"/>;
</li> </li>
<li pn="section-7.5.3-2.2"> <li>
<bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in <bcp14>MUST NOT</bcp14> place the identification-tag associated wi th the "m=" section in
the SDP 'group:BUNDLE' attribute identification-tag list associated with the SDP 'group:BUNDLE' attribute identification-tag list associated with
the BUNDLE group; and the BUNDLE group; and
</li> </li>
<li pn="section-7.5.3-2.3"> <li>
<bcp14>MUST NOT</bcp14> assign an SDP 'bundle-only' attribute to t he "m=" section. <bcp14>MUST NOT</bcp14> assign an SDP 'bundle-only' attribute to t he "m=" section.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-7.5.3-3"> <t>
For the other bundled "m=" sections within the BUNDLE group, the offer er follows the procedures For the other bundled "m=" sections within the BUNDLE group, the offer er follows the procedures
in <xref target="sec-sdp-oa-mod" format="default" sectionFormat="of" d erivedContent="Section 7.5"/>. in <xref target="sec-sdp-oa-mod"/>.
</t> </t>
<t indent="0" pn="section-7.5.3-4"> <t>
<xref target="sec-example-off-dis" format="default" sectionFormat="of" <xref target="sec-example-off-dis"/>
derivedContent="Section 18.5"/>
shows an example of an offer and answer for disabling an "m=" section within a shows an example of an offer and answer for disabling an "m=" section within a
BUNDLE group. BUNDLE group.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-sdp-oa-sip" toc="include" numbered="true" removeInRFC <section anchor="sec-sdp-oa-sip">
="false" pn="section-7.6"> <name>3PCC Considerations</name>
<name slugifiedName="name-modifying-the-session-sip">3PCC Considerations <t>
</name> In some third-party call control (3PCC) scenarios, a new session will be
<t indent="0" pn="section-7.6-1"> established between an endpoint that is currently part of an ongoing
In some 3rd Party Call Control (3PCC) scenarios a new session will be session and an endpoint that is not currently part of an ongoing
established between an endpoint that is currently part of an ongoing session. In this situation, the endpoint that is not part of a
session and an endpoint that is not currently part of an ongoing session, while expecting an initial offer, can receive an SDP offer
session. In this situation, the endpoint that is not part of a session created as a subsequent offer. The text below describes how this can
, occur with the Session Initiation Protocol (SIP) <xref target="RFC3261"/>.
while expecting an initial offer, can receive an SDP offer created as </t>
a subsequent offer. The text below describes how this can occur with
the Session Initiation Protocol (SIP) <xref format="default" target="R
FC3261"
sectionFormat="of" derivedContent="RFC3261"/>.
</t>
<t>
SIP allows a User Agent Client (UAC) to send a re-INVITE request witho
ut
an SDP body (sometimes referred to as an empty re-INVITE). In such cas
es,
the User Agent Server (UAS) will include an SDP offer in the associate
d
200 (OK) response, and when the UAS is a part of an ongoing SIP sessio
n,
this offer will be a subsequent offer. This offer will be received
by the 3PCC controller (UAC) and then forwarded to another User Agent
(UA).
When that UA is not part of an ongoing SIP session, as noted above,
it will process the offer as an initial SDP offer.
</t>
<t> <t>
When the BUNDLE mechanism is used, an initial BUNDLE offer is construc SIP <xref target="RFC3261"/> allows
ted using a User Agent Client (UAC) to send a re-INVITE request without an SDP b
different rules than subsequent BUNDLE offers, and it cannot be assume ody (sometimes referred to as an "empty re-INVITE").
d that a In such cases, the User Agent Server (UAS) will include an SDP Offer i
UA is able to correctly process a subsequent BUNDLE offer as an initia n the associated 200 (OK) response; when the UAS is a part of an
l BUNDLE offer. ongoing SIP session, this offer will be a subsequent offer. This
Therefore, the 3PCC controller SHOULD take actions to mitigate this offer will be received by the 3PCC controller (UAC) and then
problem, and e.g., rewrite the subsequent BUNDLE offer into a valid forwarded to another User Agent (UA). When that UA is not part of an
initial BUNDLE offer (<xref target="sec-sdp-oa-ino" format="default" ongoing SIP session, as noted above, it will process the offer as an
sectionFormat="of" derivedContent="Section 7.2"/>), before it forwards initial SDP offer. </t>
the BUNDLE offer to a UA. <t>
When the BUNDLE mechanism is used, an initial BUNDLE offer is
constructed using different rules than subsequent BUNDLE offers, and
it cannot be assumed that a UA is able to correctly process a
subsequent BUNDLE offer as an initial BUNDLE offer. Therefore, the
3PCC controller <bcp14>SHOULD</bcp14> take action to mitigate this problem,
e.g., rewrite the subsequent BUNDLE offer into a valid initial BUNDLE
offer (<xref target="sec-sdp-oa-ino"/>), before it forwards the BUNDLE offer
to a UA.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-protocol-id" toc="include" numbered="true" removeInRFC= <section anchor="sec-protocol-id">
"false" pn="section-8"> <name>Protocol Identification</name>
<name slugifiedName="name-protocol-identification">Protocol Identification <t>
</name>
<t indent="0" pn="section-8-1">
Each "m=" section within a BUNDLE group <bcp14>MUST</bcp14> use the same t ransport- Each "m=" section within a BUNDLE group <bcp14>MUST</bcp14> use the same t ransport-
layer protocol. If bundled "m=" sections use different upper-layer protoco ls layer protocol. If bundled "m=" sections use different upper-layer protoco ls
on top of the transport-layer protocol, there <bcp14>MUST</bcp14> exist a publicly on top of the transport-layer protocol, there <bcp14>MUST</bcp14> exist a publicly
available specification that describes how a mechanism associates available specification that describes how a mechanism associates
received data with the correct protocol for this particular protocol combi nation. received data with the correct protocol for this particular protocol combi nation.
</t> </t>
<t indent="0" pn="section-8-2"> <t>
In addition, if received data can be associated with more than In addition, if received data can be associated with more than
one bundled "m=" section, there <bcp14>MUST</bcp14> exist a publicly avail able one bundled "m=" section, there <bcp14>MUST</bcp14> exist a publicly avail able
specification that describes a mechanism for associating the specification that describes a mechanism for associating the
received data with the correct "m=" section. received data with the correct "m=" section.
</t> </t>
<t indent="0" pn="section-8-3"> <t>
This document describes a mechanism to identify the This document describes a mechanism to identify the
protocol of received data among the Session Traversal Utilities for NAT (S TUN), DTLS, and the Secure Real-time Transport Protocol (SRTP) protocol of received data among the Session Traversal Utilities for NAT (S TUN), Datagram Transport Layer Security (DTLS), and the Secure Real-time Transpo rt Protocol (SRTP)
(in any combination) when UDP is used as a transport-layer protocol, (in any combination) when UDP is used as a transport-layer protocol,
but it does not describe how to identify different protocols transported o n but it does not describe how to identify different protocols transported o n
DTLS. DTLS.
While the mechanism is generally applicable to other protocols and While the mechanism is generally applicable to other protocols and
transport-layer protocols, any such use requires further specification transport-layer protocols, any such use requires further specification
that encompasses how to multiplex multiple protocols on a given transport- layer protocol that encompasses how to multiplex multiple protocols on a given transport- layer protocol
and how to associate received data with the correct protocols. and how to associate received data with the correct protocols.
</t> </t>
<section anchor="sec-packets-id-sds" toc="include" numbered="true" removeI <section anchor="sec-packets-id-sds">
nRFC="false" pn="section-8.1"> <name>STUN, DTLS, and SRTP</name>
<name slugifiedName="name-stun-dtls-and-srtp">STUN, DTLS, and SRTP</name <t>
> <xref target="RFC5764" sectionFormat="of" section="5.1.2"/> describes a
<t indent="0" pn="section-8.1-1">
Section 5.1.2 of <xref format="default" target="RFC5764" sectionFormat="
of" derivedContent="RFC5764"/> describes a
mechanism to identify the protocol of a received packet among the STUN, DTLS, and mechanism to identify the protocol of a received packet among the STUN, DTLS, and
SRTP protocols (in any combination). SRTP protocols (in any combination).
If an offer or answer includes a bundled "m=" section that represents th ese protocols, the offerer If an offer or answer includes a bundled "m=" section that represents th ese protocols, the offerer
or answerer <bcp14>MUST</bcp14> support the mechanism described in <xref format="default" target="RFC5764" sectionFormat="of" derivedContent="RFC5764"/> , and no explicit negotiation is required in order to indicate support or answerer <bcp14>MUST</bcp14> support the mechanism described in <xref target="RFC5764"/>, and no explicit negotiation is required in order to indicat e support
and usage of the mechanism. and usage of the mechanism.
</t> </t>
<t indent="0" pn="section-8.1-2"> <t>
<xref format="default" target="RFC5764" sectionFormat="of" derivedConten <xref target="RFC5764"/> does not describe how to identify
t="RFC5764"/> does not describe how to identify
different protocols transported on DTLS, only how to identify the DTLS p rotocol itself. If different protocols transported on DTLS, only how to identify the DTLS p rotocol itself. If
multiple protocols are transported on DTLS, there <bcp14>MUST</bcp14> ex ist a specification describing a multiple protocols are transported on DTLS, there <bcp14>MUST</bcp14> ex ist a specification describing a
mechanism for identifying each individual protocol. In addition, if a re ceived DTLS packet mechanism for identifying each individual protocol. In addition, if a re ceived DTLS packet
can be associated with more than one "m=" section, there <bcp14>MUST</bc p14> exist a specification that can be associated with more than one "m=" section, there <bcp14>MUST</bc p14> exist a specification that
describes a mechanism for associating the received DTLS packets with the correct "m=" section. describes a mechanism for associating the received DTLS packets with the correct "m=" section.
</t> </t>
<t indent="0" pn="section-8.1-3"> <t>
<xref format="default" target="sec-rtp-pt" sectionFormat="of" derivedCon <xref target="sec-rtp-pt"/> describes how to
tent="Section 9.2"/> describes how to
associate the packets in a received SRTP stream with the correct "m=" se ction. associate the packets in a received SRTP stream with the correct "m=" se ction.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-rtp" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-rtp">
pn="section-9"> <name>RTP Considerations</name>
<name slugifiedName="name-rtp-considerations">RTP Considerations</name> <section anchor="sec-rtp-sessions">
<section anchor="sec-rtp-sessions" toc="include" numbered="true" removeInR <name>Single RTP Session</name>
FC="false" pn="section-9.1"> <t>
<name slugifiedName="name-single-rtp-session">Single RTP Session</name>
<t indent="0" pn="section-9.1-1">
All RTP-based media within a single BUNDLE group belong to a All RTP-based media within a single BUNDLE group belong to a
single RTP session <xref format="default" target="RFC3550" sectionFo rmat="of" derivedContent="RFC3550"/>. single RTP session <xref target="RFC3550"/>.
</t> </t>
<t indent="0" pn="section-9.1-2"> <t>
Since a single BUNDLE transport is used for sending and receiving bu ndled media, Since a single BUNDLE transport is used for sending and receiving bu ndled media,
the symmetric RTP mechanism <xref format="default" target="RFC4961" sectionFormat="of" derivedContent="RFC4961"/> the symmetric RTP mechanism <xref target="RFC4961"/>
<bcp14>MUST</bcp14> be used for RTP-based bundled media. <bcp14>MUST</bcp14> be used for RTP-based bundled media.
</t> </t>
<t indent="0" pn="section-9.1-3"> <t>
Since a single RTP session is used for each BUNDLE group, all Since a single RTP session is used for each BUNDLE group, all
"m=" sections representing RTP-based media within a BUNDLE group wil l "m=" sections representing RTP-based media within a BUNDLE group wil l
share a single Synchronization Source (SSRC) numbering space <xref f ormat="default" target="RFC3550" sectionFormat="of" derivedContent="RFC3550"/>. share a single synchronization source (SSRC) numbering space <xref t arget="RFC3550"/>.
</t> </t>
<t indent="0" pn="section-9.1-4"> <t>
The following rules and restrictions apply for a single RTP The following rules and restrictions apply for a single RTP
session: session:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-9 <ul>
.1-5"> <li>
<li pn="section-9.1-5.1">
A specific payload type value can be used in multiple bundled "m =" sections A specific payload type value can be used in multiple bundled "m =" sections
only if each codec associated with the payload type number share s an identical only if each codec associated with the payload type number share s an identical
codec configuration (<xref format="default" target="sec-rtp-sess ions-pt" sectionFormat="of" derivedContent="Section 9.1.1"/>). codec configuration (<xref target="sec-rtp-sessions-pt"/>).
</li> </li>
<li pn="section-9.1-5.2"> <li>
The proto value in each bundled RTP-based "m=" section <bcp14>MU ST</bcp14> be identical The proto value in each bundled RTP-based "m=" section <bcp14>MU ST</bcp14> be identical
(e.g., RTP/AVPF). (e.g., RTP/AVPF).
</li> </li>
<li pn="section-9.1-5.3">
The RTP MID header extension <bcp14>MUST</bcp14> be enabled, by <li>
including The RTP MID header extension <bcp14>MUST</bcp14> be enabled by i
an SDP 'extmap' attribute <xref format="default" target="RFC8285 ncluding
" sectionFormat="of" derivedContent="RFC8285"/>, an SDP 'extmap' attribute <xref target="RFC8285"/>,
with a 'urn:ietf:params:rtp- hdrext:sdes:mid' URI value defined with a 'urn:ietf:params:rtp- hdrext:sdes:mid' URI value defined
in this specification, in each in this specification in each
bundled RTP-based "m=" section in every offer and answer. bundled RTP-based "m=" section in every offer and answer.
</li> </li>
<li pn="section-9.1-5.4"> <li>
A given SSRC <bcp14>MUST NOT</bcp14> transmit RTP packets using payload types that A given SSRC <bcp14>MUST NOT</bcp14> transmit RTP packets using payload types that
originate from different bundled "m=" sections. originate from different bundled "m=" sections.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-9.1-6"> <t indent="3">
NOTE: The last bullet above is to avoid sending multiple media types NOTE: The last bullet above is to avoid sending multiple media types
from the same SSRC. If transmission of multiple media types are done from the same SSRC. If transmission of multiple media types is done
with time overlap, RTP and RTCP fail to function. Even if done in with time overlap, RTP and RTCP fail to function. Even if done in th
proper sequence, this causes RTP timestamp rate switching issues e proper sequence, this causes RTP timestamp rate switching issues
<xref format="default" target="RFC7160" sectionFormat="of" derivedCo <xref target="RFC7160"/>. However,
ntent="RFC7160"/>. However,
once an SSRC has left the RTP session (by sending an RTCP BYE packet ), once an SSRC has left the RTP session (by sending an RTCP BYE packet ),
that SSRC can be reused by another source (possibly associated that SSRC can be reused by another source (possibly associated
with a different bundled "m=" section) after a delay of 5 RTCP repor ting intervals with a different bundled "m=" section) after a delay of 5 RTCP repor ting intervals
(the delay is to ensure the SSRC has timed out, in case the RTCP BYE (the delay is to ensure the SSRC has timed out in case the RTCP BYE
packet was lost <xref format="default" target="RFC3550" sectionForma packet was lost <xref target="RFC3550"/>).
t="of" derivedContent="RFC3550"/>).
</t> </t>
<t indent="0" pn="section-9.1-7"> <t>
<xref format="default" target="RFC7657" sectionFormat="of" derivedCo <xref target="RFC7657"/> defines Differentiated Services
ntent="RFC7657"/> defines Differentiated Services
(Diffserv) considerations for RTP-based bundled media sent using a m ixture of Diffserv Codepoints. (Diffserv) considerations for RTP-based bundled media sent using a m ixture of Diffserv Codepoints.
</t> </t>
<section anchor="sec-rtp-sessions-pt" toc="include" numbered="true" remo <section anchor="sec-rtp-sessions-pt">
veInRFC="false" pn="section-9.1.1"> <name>Payload Type (PT) Value Reuse</name>
<name slugifiedName="name-payload-type-pt-value-reuse">Payload Type (P <t>
T) Value Reuse</name>
<t indent="0" pn="section-9.1.1-1">
Multiple bundled "m=" sections might describe RTP-based media. As al l RTP-based Multiple bundled "m=" sections might describe RTP-based media. As al l RTP-based
media associated with a BUNDLE group belong to the same RTP session, in order media associated with a BUNDLE group belong to the same RTP session, in order
for a given payload type value to be used inside more than one bundl ed "m=" section, for a given payload type value to be used inside more than one bundl ed "m=" section,
all codecs associated with the payload type number <bcp14>MUST</bcp1 4> share an identical codec all codecs associated with the payload type number <bcp14>MUST</bcp1 4> share an identical codec
configuration. This means that the codecs <bcp14>MUST</bcp14> share the same media type, configuration. This means that the codecs <bcp14>MUST</bcp14> share the same media type,
encoding name, clock rate, and any parameter that can affect the cod ec configuration encoding name, clock rate, and any parameter that can affect the cod ec configuration
and packetization. <xref format="default" target="RFC8859" sectionFo rmat="of" derivedContent="RFC8859"/> lists SDP attributes, whose attribute and packetization. <xref target="RFC8859"/> lists SDP attributes who se attribute
values are required to be identical for all codecs that use the values are required to be identical for all codecs that use the
same payload type value. same payload type value.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-rtp-pt" toc="include" numbered="true" removeInRFC="fa <section anchor="sec-rtp-pt">
lse" pn="section-9.2"> <name>Associating RTP/RTCP Streams with the Correct SDP Media Descriptio
<name slugifiedName="name-associating-rtp-rtcp-stream">Associating RTP/R n</name>
TCP Streams with the Correct SDP Media Description</name> <t>
<t indent="0" pn="section-9.2-1"> As described in <xref target="RFC3550"/>, RTP packets are associated
As described in <xref target="RFC3550" format="default" sectionForma with RTP
t="of" derivedContent="RFC3550"/>, RTP packets are associated with RTP streams <xref target="RFC7656"/>. Each RTP stream is identified by a
streams <xref target="RFC7656" format="default" sectionFormat="of" d n SSRC
erivedContent="RFC7656"/>. Each RTP stream is identified by an SSRC
value, and each RTP packet includes an SSRC field that is value, and each RTP packet includes an SSRC field that is
used to associate the packet with the correct RTP stream. used to associate the packet with the correct RTP stream.
RTCP packets also use SSRCs to identify which RTP streams the RTCP packets also use SSRCs to identify which RTP streams the
packet relates to. However, an RTCP packet can contain multiple SSRC packet relates to. However, an RTCP packet can contain multiple SSRC
fields, in the course of providing feedback or reports on different fields in the course of providing feedback or reports on different R
RTP TP
streams, and therefore can be associated with multiple such streams. streams; therefore, they can be associated with multiple such stream
s.
</t> </t>
<t indent="0" pn="section-9.2-2"> <t>
In order to be able to process received RTP/RTCP packets In order to be able to process received RTP/RTCP packets
correctly, it <bcp14>MUST</bcp14> be possible to associate an RTP st ream with correctly, it <bcp14>MUST</bcp14> be possible to associate an RTP st ream with
the correct "m=" section, as the "m=" section and SDP attributes the correct "m=" section, as the "m=" section and SDP attributes
associated with the "m=" section contains information needed to associated with the "m=" section contain information needed to
process the packets. process the packets.
</t> </t>
<t indent="0" pn="section-9.2-3"> <t>
As all RTP streams associated with a BUNDLE group use the As all RTP streams associated with a BUNDLE group use the
same transport for sending and receiving RTP/RTCP same transport for sending and receiving RTP/RTCP
packets, the local address:port combination part of the transport packets, the local address:port combination part of the transport
cannot be used to associate an RTP stream with the correct "m=" sect ion. cannot be used to associate an RTP stream with the correct "m=" sect ion.
In addition, multiple RTP streams might be associated with the same "m=" In addition, multiple RTP streams might be associated with the same "m="
section. section.
</t> </t>
<t indent="0" pn="section-9.2-4"> <t>
An offerer and answerer can inform each other which SSRC An offerer and answerer can inform each other which SSRC
values they will use for an RTP stream by using the SDP 'ssrc' values they will use for an RTP stream by using the SDP 'ssrc'
attribute <xref format="default" target="RFC5576" sectionFormat="of" derivedContent="RFC5576"/>. attribute <xref target="RFC5576"/>.
However, an offerer will not know which SSRC values the However, an offerer will not know which SSRC values the
answerer will use until the offerer has received the answer answerer will use until the offerer has received the answer
providing that information. Due to this, before the offerer has providing that information. Due to this, before the offerer has
received the answer, the offerer will not be able to associate received the answer, the offerer will not be able to associate
an RTP stream with the correct "m=" section using the SSRC value an RTP stream with the correct "m=" section using the SSRC value
associated with the RTP stream. In addition, the offerer and associated with the RTP stream. In addition, the offerer and
answerer may start using new SSRC values mid-session, without answerer may start using new SSRC values mid-session, without
informing each other about using the SDP 'ssrc' attribute. informing each other about using the SDP 'ssrc' attribute.
</t> </t>
<t indent="0" pn="section-9.2-5"> <t>
In order for an offerer and answerer to always be able to In order for an offerer and answerer to always be able to
associate an RTP stream with the correct "m=" section, the offerer associate an RTP stream with the correct "m=" section, the offerer
and answerer using the BUNDLE extension <bcp14>MUST</bcp14> support the and answerer using the BUNDLE extension <bcp14>MUST</bcp14> support the
mechanism defined in <xref format="default" target="sec-receiver-id" sectionFormat="of" derivedContent="Section 15"/>, mechanism defined in <xref target="sec-receiver-id"/>,
where the offerer and answerer insert the identification-tag associa ted where the offerer and answerer insert the identification-tag associa ted
with an "m=" section (provided by the remote peer) into RTP and RTCP with an "m=" section (provided by the remote peer) into RTP and RTCP
packets associated with a BUNDLE group. packets associated with a BUNDLE group.
</t> </t>
<t indent="0" pn="section-9.2-6"> <t>
When using this mechanism, the mapping from an SSRC to an When using this mechanism, the mapping from an SSRC to an
identification-tag is carried in RTP header extensions or RTCP SDES identification-tag is carried in RTP header extensions or RTCP SDES
packets, as specified in <xref format="default" target="sec-receive packets, as specified in <xref target="sec-receiver-id"/>.
r-id" sectionFormat="of" derivedContent="Section 15"/>. Since a compound RTCP packet can contain multiple RTCP SDES packets
Since a compound RTCP packet can contain multiple RTCP SDES packets
,
and each RTCP SDES packet can contain multiple chunks, a single RTC P and each RTCP SDES packet can contain multiple chunks, a single RTC P
packet can contain several mappings of SSRC to identification-tag. The packet can contain several mappings of SSRC to identification-tag. The
offerer and answerer maintain tables used for routing that are upda ted offerer and answerer maintain tables used for routing that are upda ted
each time an RTP/RTCP packet contains new information that affects how each time an RTP/RTCP packet contains new information that affects how
packets are to be routed. packets are to be routed.
</t> </t>
<t indent="0" pn="section-9.2-7"> <t>
However, some legacy implementations may not include this identifica tion-tag However, some legacy implementations may not include this identifica tion-tag
in their RTP and RTCP traffic when using the BUNDLE mechanism and in their RTP and RTCP traffic when using the BUNDLE mechanism and
instead use a mechanism based on the payload type to associate RTP s treams instead use a mechanism based on the payload type to associate RTP s treams
with SDP "m=" sections. In this situation, each "m=" section needs to with SDP "m=" sections. In this situation, each "m=" section needs to
use unique payload type values, in order for the payload type to be a use unique payload type values in order for the payload type to be a
reliable indicator of the relevant "m=" section for the RTP stream. If an reliable indicator of the relevant "m=" section for the RTP stream. If an
implementation fails to ensure unique payload type values, it will b e implementation fails to ensure unique payload type values, it will b e
impossible to associate the RTP stream using that payload type value impossible to associate the RTP stream using that payload type value
to a particular "m=" section. to a particular "m=" section.
Note that when using the payload type to associate RTP streams with Note that when using the payload type to associate RTP streams with
"m=" sections, an RTP stream, identified by its SSRC, will be mapped "m=" sections, an RTP stream, identified by its SSRC, will be mapped
to an "m=" section when the first packet of that RTP stream is to an "m=" section when the first packet of that RTP stream is
received, and the mapping will not be changed even if the payload received, and the mapping will not be changed even if the payload
type used by that RTP stream changes. In other words, the SSRC type used by that RTP stream changes. In other words, the SSRC
cannot "move" to a different "m=" section simply by changing the cannot "move" to a different "m=" section simply by changing the
payload type. payload type.
</t> </t>
<t indent="0" pn="section-9.2-8"> <t>
Applications can implement RTP stacks in different Applications can implement RTP stacks in different
ways. The algorithm below details one way that RTP streams can be ways. The algorithm below details one way that RTP streams can be
associated with "m=" sections, but it is not meant to be prescripti ve associated with "m=" sections, but it is not meant to be prescripti ve
about exactly how an RTP stack needs to be implemented. about exactly how an RTP stack needs to be implemented.
Applications <bcp14>MAY</bcp14> use any algorithm that achieves equ ivalent results to Applications <bcp14>MAY</bcp14> use any algorithm that achieves equ ivalent results to
those described in the algorithm below. those described in the algorithm below.
</t> </t>
<t indent="0" pn="section-9.2-9"> <t>
To prepare to associate RTP streams with the correct To prepare to associate RTP streams with the correct
"m=" section, the following steps <bcp14>MUST</bcp14> be followed f or each BUNDLE group: "m=" section, the following steps <bcp14>MUST</bcp14> be followed f or each BUNDLE group:
</t> </t>
<ul empty="false" spacing="normal" bare="false" indent="3" pn="section-9 <ul>
.2-10"> <li>
<li pn="section-9.2-10.1">
Construct a table mapping a MID to an "m=" section for each "m= " Construct a table mapping a MID to an "m=" section for each "m= "
section in this BUNDLE group. Note that an "m=" section may onl y section in this BUNDLE group. Note that an "m=" section may onl y
have one MID. have one MID.
</li> </li>
<li pn="section-9.2-10.2"> <li>
Construct a table mapping SSRCs of incoming RTP streams to an " m=" section for Construct a table mapping SSRCs of incoming RTP streams to an " m=" section for
each "m=" section in this BUNDLE group and for each SSRC each "m=" section in this BUNDLE group and for each SSRC
configured for receiving in that "m=" section. configured for receiving in that "m=" section.
</li> </li>
<li pn="section-9.2-10.3"> <li>
Construct a table mapping the SSRC of each outgoing RTP stream Construct a table mapping the SSRC of each outgoing RTP stream
to an "m=" section for each "m=" section in this BUNDLE group a nd for each SSRC to an "m=" section for each "m=" section in this BUNDLE group a nd for each SSRC
configured for sending in that "m=" section. configured for sending in that "m=" section.
</li> </li>
<li pn="section-9.2-10.4"> <li>
Construct a table mapping a payload type to an "m=" section for Construct a table mapping a payload type to an "m=" section for
each "m=" section in the BUNDLE group and for each payload type each "m=" section in the BUNDLE group and for each payload type
configured for receiving in that "m=" section. If any payload configured for receiving in that "m=" section. If any payload
type is configured for receiving in more than one "m=" section type is configured for receiving in more than one "m=" section
in the BUNDLE group, do not include it in the table, as it in the BUNDLE group, do not include it in the table, as it
cannot be used to uniquely identify an "m=" section. cannot be used to uniquely identify an "m=" section.
</li> </li>
<li pn="section-9.2-10.5"> <li>
Note that for each of these tables, there can only be one Note that for each of these tables, there can only be one
mapping for any given key (MID, SSRC, or PT). In other mapping for any given key (MID, SSRC, or PT). In other
words, the tables are not multimaps. words, the tables are not multimaps.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-9.2-11"> <t>
As "m=" sections are added or removed from the BUNDLE groups, or As "m=" sections are added or removed from the BUNDLE groups or
their configurations are changed, the tables above <bcp14>MUST</bcp 14> also be their configurations are changed, the tables above <bcp14>MUST</bcp 14> also be
updated. updated.
</t> </t>
<t indent="0" pn="section-9.2-12"> <t>
When an RTP packet is received, it <bcp14>MUST</bcp14> be delivered to the RTP When an RTP packet is received, it <bcp14>MUST</bcp14> be delivered to the RTP
stream corresponding to its SSRC. That RTP stream <bcp14>MUST</bcp1 4> then be stream corresponding to its SSRC. That RTP stream <bcp14>MUST</bcp1 4> then be
associated with the correct "m=" section within a BUNDLE group, for associated with the correct "m=" section within a BUNDLE group for
additional processing, according to the following steps: additional processing, according to the following steps:
</t> </t>
<ul empty="false" spacing="normal" bare="false" indent="3" pn="section-9 <ul>
.2-13"> <li>
<li pn="section-9.2-13.1">
If the MID associated with the RTP stream is not in the If the MID associated with the RTP stream is not in the
table mapping a MID to an "m=" section, then the RTP stream is not table mapping a MID to an "m=" section, then the RTP stream is not
decoded, and the payload data is discarded. decoded, and the payload data is discarded.
</li> </li>
<li pn="section-9.2-13.2"> <li>
If the packet has a MID, and the packet's extended sequence num If the packet has a MID and the packet's extended sequence numb
ber er
is greater than that of the last MID update, as discussed in is greater than that of the last MID update, as discussed in
<xref target="RFC7941" sectionFormat="comma" section="4.2.6" fo <xref target="RFC7941" sectionFormat="comma" section="4.2.6"/>,
rmat="default" derivedLink="https://rfc-editor.org/rfc/rfc7941#section-4.2.6" de update the MID associated
rivedContent="RFC7941"/>, update the MID associated with the RTP stream to match the MID carried in the RTP packet
with the RTP stream to match the MID carried in the RTP packet, and then
and then
update the mapping tables to include an entry that maps the SSR C of update the mapping tables to include an entry that maps the SSR C of
that RTP stream to the "m=" section for that MID. that RTP stream to the "m=" section for that MID.
</li> </li>
<li pn="section-9.2-13.3"> <li>
If the SSRC of the RTP stream is in the incoming SSRC If the SSRC of the RTP stream is in the incoming SSRC
mapping table, check that the payload type used by the RTP mapping table, check that the payload type used by the RTP
stream matches a payload type included on the matching stream matches a payload type included in the matching
"m=" section. If so, associate the RTP stream with that "m=" section. If so, associate the RTP stream with that
"m=" section. Otherwise, the RTP stream is not decoded, and the "m=" section. Otherwise, the RTP stream is not decoded, and the
payload data is discarded. payload data is discarded.
</li> </li>
<li pn="section-9.2-13.4"> <li>
If the payload type used by the RTP stream is in the If the payload type used by the RTP stream is in the
payload type table, update the incoming SSRC mapping table payload type table, update the incoming SSRC mapping table
to include an entry that maps the RTP stream's SSRC to the to include an entry that maps the RTP stream's SSRC to the
"m=" section for that payload type. Associate the RTP stream "m=" section for that payload type. Associate the RTP stream
with the corresponding "m=" section. with the corresponding "m=" section.
</li> </li>
<li pn="section-9.2-13.5"> <li>
Otherwise, mark the RTP stream as "not for decoding" and Otherwise, mark the RTP stream as "not for decoding" and
discard the payload. discard the payload.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-9.2-14"> <t>
If the RTP packet contains one or more Contributing Source (CSRC) If the RTP packet contains one or more contributing source (CSRC)
identifiers, then each CSRC is looked up in the incoming SSRC table, identifiers, then each CSRC is looked up in the incoming SSRC table,
and a copy of the RTP packet is associated with the corresponding and a copy of the RTP packet is associated with the corresponding
"m=" section for additional processing. "m=" section for additional processing.
</t> </t>
<t indent="0" pn="section-9.2-15"> <t>
For each RTCP packet received (including each RTCP packet that is For each RTCP packet received (including each RTCP
part of a compound RTCP packet), the packet is processed as usual packet that is part of a compound RTCP packet), the
by packet is processed as usual by the RTP layer, then
the RTP layer, then associated with the appropriate "m=" sections, associated with the appropriate "m=" sections and
and processed for the RTP streams represented by those "m="
processed for the RTP streams represented by those "m=" sections. sections. This routing is type dependent, as each kind
This routing is type dependent, as each kind of RTCP packet has it of RTCP packet has its own mechanism for associating it
s own with the relevant RTP streams.
mechanism for associating it with the relevant RTP streams.
</t> </t>
<t indent="0" pn="section-9.2-16"> <t>
RTCP packets that cannot be associated with an appropriate "m=" se RTCP packets that cannot be associated with an
ction appropriate "m=" section <bcp14>MUST</bcp14> still be
<bcp14>MUST</bcp14> still be processed as usual by the RTP layer, processed as usual by the RTP layer, which updates the
which updates the metadata metadata associated with the corresponding RTP
associated with the corresponding RTP streams. This situation can streams. This situation can occur with certain
occur with multiparty RTP topologies or when RTCP packets are sent
certain multiparty RTP topologies or when RTCP packets are sent co containing a subset of the SDES information.
ntaining
a subset of the SDES information.
</t> </t>
<t indent="0" pn="section-9.2-17"> <t>
Additional rules for processing various types of RTCP packets are Additional rules for processing various types of RTCP packets are
explained below. explained below.
</t> </t>
<ul empty="false" spacing="normal" bare="false" indent="3" pn="section-9 <ul>
.2-18"> <li>
<li pn="section-9.2-18.1">
If the RTCP packet is of type SDES, for each chunk in the packet If the RTCP packet is of type SDES, for each chunk in the packet
whose SSRC is found in the incoming SSRC table, deliver a copy whose SSRC is found in the incoming SSRC table, deliver a copy
of the SDES packet to the "m=" section associated with that SSRC . of the SDES packet to the "m=" section associated with that SSRC .
In addition, for any SDES MID items contained in these chunks, In addition, for any SDES MID items contained in these chunks,
if the MID is found in the table mapping a MID to an "m=" sectio n, if the MID is found in the table mapping a MID to an "m=" sectio n,
update the incoming SSRC table to include an entry that update the incoming SSRC table to include an entry that
maps the RTP stream associated with the chunk's SSRC to the "m=" section maps the RTP stream associated with the chunk's SSRC to the "m=" section
associated with that MID, unless the packet is older than the pa cket associated with that MID, unless the packet is older than the pa cket
that most recently updated the mapping for this SSRC, as discuss ed in that most recently updated the mapping for this SSRC, as discuss ed in
<xref target="RFC7941" sectionFormat="comma" section="4.2.6" for mat="default" derivedLink="https://rfc-editor.org/rfc/rfc7941#section-4.2.6" der ivedContent="RFC7941"/>. <xref target="RFC7941" sectionFormat="comma" section="4.2.6"/>.
</li> </li>
<li pn="section-9.2-18.2"> <li>
Note that if an SDES packet is received as part of a compound RT Note that if an SDES packet is received as part of a
CP compound RTCP packet, the SSRC to "m=" section mapping
packet, the SSRC to "m=" section mapping might not exist until t might not exist until the SDES packet is handled
he (e.g., in the case where RTCP for a source is received
SDES packet is handled (e.g., in the case where RTCP for a sourc before any RTP packets).
e
is received before any RTP packets). Therefore, it can be benefi Therefore, it can be
cial beneficial for an implementation to delay RTCP packet
for an implementation to delay RTCP packet routing, such that it routing, such that it either prioritizes processing of
either prioritizes processing of the SDES item to generate or up the SDES item to generate or update the mapping or
date buffers the RTCP information that needs to be routed
the mapping or buffers the RTCP information that needs to be until the SDES item(s) has been processed.
routed until the SDES item(s) has been processed. If the
implementation is unable to follow this recommendation, the If the
consequence could be that some RTCP information from this implementation is unable to follow this
particular RTCP compound packet is not provided to higher layers recommendation, the consequence could be that some
. RTCP information from this particular RTCP compound
The impact from this is likely minor, when this information rela packet is not provided to higher layers. The impact
tes from this is likely minor when this information
to a future incoming RTP stream. relates to a future incoming RTP stream.
</li> </li>
<li pn="section-9.2-18.3"> <li>
If the RTCP packet is of type BYE, it indicates that the RTP str eams If the RTCP packet is of type BYE, it indicates that the RTP str eams
referenced in the packet are ending. Therefore, for each SSRC referenced in the packet are ending. Therefore, for each SSRC
indicated in the packet that is found in the incoming SSRC table , indicated in the packet that is found in the incoming SSRC table ,
first deliver a copy of the BYE packet to the "m=" section assoc iated first deliver a copy of the BYE packet to the "m=" section assoc iated
with that SSRC, and then remove the entry for that SSRC from the with that SSRC, and then remove the entry for that SSRC from the
incoming SSRC table after an appropriate delay to incoming SSRC table after an appropriate delay to
account for "straggler packets", as specified in <xref target="R FC3550" sectionFormat="comma" section="6.2.1" format="default" derivedLink="http s://rfc-editor.org/rfc/rfc3550#section-6.2.1" derivedContent="RFC3550"/>. account for "straggler packets", as specified in <xref target="R FC3550" sectionFormat="comma" section="6.2.1"/>.
</li> </li>
<li pn="section-9.2-18.4"> <li>
If the RTCP packet is of type Sender Report (SR) or Receiver Rep If the RTCP packet is of type sender report (SR) or receiver rep
ort (RR), for each report block in ort (RR), for each report block in
the report whose "SSRC of source" is found in the outgoing the report whose "SSRC of source" is found in the outgoing
SSRC table, deliver a copy of the SR or RR packet to the "m=" se ction SSRC table, deliver a copy of the SR or RR packet to the "m=" se ction
associated with that SSRC. In addition, if the packet is of type associated with that SSRC. In addition, if the packet is of type
SR, and the sender SSRC for the packet is found in the SR and the sender SSRC for the packet is found in the
incoming SSRC table, deliver a copy of the SR packet to the "m=" section incoming SSRC table, deliver a copy of the SR packet to the "m=" section
associated with that SSRC. associated with that SSRC.
</li> </li>
<li pn="section-9.2-18.5"> <li>
If the implementation supports the RTCP Extended Report (XR) and the packet is of If the implementation supports the RTCP Extended Report (XR) and the packet is of
type XR, as defined in <xref target="RFC3611" format="default" s ectionFormat="of" derivedContent="RFC3611"/>, type XR, as defined in <xref target="RFC3611"/>,
for each report block in the report whose "SSRC of source" for each report block in the report whose "SSRC of source"
is found in the outgoing SSRC table, deliver a copy of the is found in the outgoing SSRC table, deliver a copy of the
XR packet to the "m=" section associated with that SSRC. XR packet to the "m=" section associated with that SSRC.
In addition, if the sender SSRC for the packet is found in the In addition, if the sender SSRC for the packet is found in the
incoming SSRC table, deliver a copy of the XR packet to the "m=" section incoming SSRC table, deliver a copy of the XR packet to the "m=" section
associated with that SSRC. associated with that SSRC.
</li> </li>
<li pn="section-9.2-18.6"> <li>
If the RTCP packet is a feedback message of type RTPFB (transpor t-layer FB If the RTCP packet is a feedback message of type RTPFB (transpor t-layer FB
message) or PSFB (payload-specific FB message), message) or PSFB (payload-specific FB message),
as defined in <xref target="RFC4585" format="default" sectionFor mat="of" derivedContent="RFC4585"/>, it will contain a as defined in <xref target="RFC4585"/>, it will contain a
media source SSRC, and this SSRC is used for routing certain media source SSRC, and this SSRC is used for routing certain
subtypes of feedback messages. However, several subtypes of subtypes of feedback messages. However, several subtypes of
PSFB and RTPFB messages include a target SSRC(s) in a section ca lled PSFB and RTPFB messages include a target SSRC(s) in a section ca lled
Feedback Control Information (FCI). For these messages, Feedback Control Information (FCI). For these messages,
the target SSRC(s) is used for routing. the target SSRC(s) is used for routing.
</li> </li>
<li pn="section-9.2-18.7"> <li>
<t indent="0" pn="section-9.2-18.7.1"> <t>
If the RTCP packet is a feedback packet that does not include If the RTCP packet is a feedback packet that does not include
target SSRCs in its FCI section, and the media source SSRC is target SSRCs in its FCI section, and the media source SSRC is
found in the outgoing SSRC table, deliver the found in the outgoing SSRC table, deliver the
feedback packet to the "m=" section associated with that SSRC. feedback packet to the "m=" section associated with that SSRC.
RTPFB and PSFB types that are handled in this way include: RTPFB and PSFB types that are handled in this way include:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="sectio <dl>
n-9.2-18.7.2"> <dt>Generic NACK:</dt>
<li pn="section-9.2-18.7.2.1"> <dd>(PT=RTPFB, FMT=1) <xref target="RFC4585"/></dd>
<dl newline="false" spacing="normal" indent="3" pn="section-9.2- <dt>Picture Loss Indication (PLI):</dt>
18.7.2.1.1"> <dd>(PT=PSFB, FMT=1) <xref target="RFC4585"/></dd>
<dt pn="section-9.2-18.7.2.1.1.1">Generic NACK:</dt> <dt>Slice Loss Indication (SLI):</dt>
<dd pn="section-9.2-18.7.2.1.1.2">(PT=RTPFB, FMT=1) <xref targ <dd> (PT=PSFB, FMT=2) <xref target="RFC4585"/></dd>
et="RFC4585" format="default" sectionFormat="of" derivedContent="RFC4585"/>.</dd <dt>Reference Picture Selection Indication (RPSI):</dt>
> <dd>(PT=PSFB, FMT=3) <xref target="RFC4585"/></dd>
<dt pn="section-9.2-18.7.2.1.1.3">Picture Loss Indication (PLI
):</dt>
<dd pn="section-9.2-18.7.2.1.1.4">(PT=PSFB, FMT=1) <xref targe
t="RFC4585" format="default" sectionFormat="of" derivedContent="RFC4585"/>.</dd>
<dt pn="section-9.2-18.7.2.1.1.5">Slice Loss Indication (SLI):
</dt>
<dd pn="section-9.2-18.7.2.1.1.6"> (PT=PSFB, FMT=2) <xref targ
et="RFC4585" format="default" sectionFormat="of" derivedContent="RFC4585"/>.</dd
>
<dt pn="section-9.2-18.7.2.1.1.7">Reference Picture Selection
Indication (RPSI):</dt>
<dd pn="section-9.2-18.7.2.1.1.8">(PT=PSFB, FMT=3) <xref targe
t="RFC4585" format="default" sectionFormat="of" derivedContent="RFC4585"/>.</dd>
</dl> </dl>
</li> </li>
</ul> </ul>
</li> <ul>
</ul> <li>
<ul empty="false" bare="false" indent="3" spacing="normal" pn="section-9
.2-19">
<li pn="section-9.2-19.1">
If the RTCP packet is a feedback message that does include a tar get If the RTCP packet is a feedback message that does include a tar get
SSRC(s) in its FCI section, it can either be a request or a SSRC(s) in its FCI section, it can either be a request or a
notification. Requests reference an RTP stream that is being notification. Requests reference an RTP stream that is being
sent by the message recipient, whereas notifications are respons es sent by the message recipient, whereas notifications are respons es
to an earlier request and therefore reference an RTP stream that to an earlier request and therefore reference an RTP stream that
is being received by the message recipient. is being received by the message recipient.
</li> </li>
<li pn="section-9.2-19.2"> <li>
<t indent="0" pn="section-9.2-19.2.1"> <t>
If the RTCP packet is a feedback request that includes a target SSRC(s), If the RTCP packet is a feedback request that includes a target SSRC(s),
for each target SSRC that is found in the outgoing SSRC table, for each target SSRC that is found in the outgoing SSRC table,
deliver a copy of the RTCP packet to the "m=" section associated with deliver a copy of the RTCP packet to the "m=" section associated with
that SSRC. PSFB and RTPFB types that are handled in this way inc lude: that SSRC. PSFB and RTPFB types that are handled in this way inc lude:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="sectio <dl>
n-9.2-19.2.2"> <dt>Full Intra Request (FIR):</dt>
<li pn="section-9.2-19.2.2.1"> <dd>(PT=PSFB, FMT=4) <xref target="RFC5104"/>
<dl newline="false" spacing="normal" indent="3" pn="section-9.2-
19.2.2.1.1">
<dt pn="section-9.2-19.2.2.1.1.1">Full Intra Request (FIR):</d
t>
<dd pn="section-9.2-19.2.2.1.1.2">(PT=PSFB, FMT=4) <xref targe
t="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>.
</dd> </dd>
<dt pn="section-9.2-19.2.2.1.1.3">Temporal-Spatial Trade-off R <dt>Temporal-Spatial Trade-off Request (TSTR):</dt>
equest (TSTR):</dt> <dd>(PT=PSFB, FMT=5) <xref target="RFC5104"/>
<dd pn="section-9.2-19.2.2.1.1.4">(PT=PSFB, FMT=5) <xref targe
t="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>.
</dd> </dd>
<dt pn="section-9.2-19.2.2.1.1.5">H.271 Video Back Channel Mes <dt>H.271 Video Back Channel Message (VBCM):</dt>
sage (VBCM):</dt> <dd>(PT=PSFB, FMT=7) <xref target="RFC5104"/>
<dd pn="section-9.2-19.2.2.1.1.6">(PT=PSFB, FMT=7) <xref targe
t="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>.
</dd> </dd>
<dt pn="section-9.2-19.2.2.1.1.7">Temporary Maximum Media Stre <dt>Temporary Maximum Media Stream Bit Rate Request (TMMBR):</
am Bit Rate Request (TMMBR):</dt> dt>
<dd pn="section-9.2-19.2.2.1.1.8">(PT=RTPFB, FMT=3) <xref targ <dd>(PT=RTPFB, FMT=3) <xref target="RFC5104"/>
et="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>.
</dd> </dd>
<dt pn="section-9.2-19.2.2.1.1.9">Layer Refresh Request (LRR): <dt>Layer Refresh Request (LRR):</dt>
</dt> <dd>(PT=PSFB, FMT=10) <xref target="I-D.ietf-avtext-lrr"/>.
<dd pn="section-9.2-19.2.2.1.1.10">(PT=PSFB, FMT=10) <xref tar
get="I-D.ietf-avtext-lrr" format="default" sectionFormat="of" derivedContent="LL
R-RTCP"/>.
</dd> </dd>
</dl> </dl>
</li> </li>
</ul> </ul>
</li> <ul>
</ul> <li>
<ul empty="false" bare="false" indent="3" spacing="normal" pn="section-9 <t>
.2-20">
<li pn="section-9.2-20.1">
<t indent="0" pn="section-9.2-20.1.1">
If the RTCP packet is a feedback notification that includes a ta rget SSRC(s), If the RTCP packet is a feedback notification that includes a ta rget SSRC(s),
for each target SSRC that is found in the incoming SSRC table, for each target SSRC that is found in the incoming SSRC table,
deliver a copy of the RTCP packet to the "m=" section associated with deliver a copy of the RTCP packet to the "m=" section associated with
the RTP stream with a matching SSRC. PSFB and RTPFB types that a re handled in this way include: the RTP stream with a matching SSRC. PSFB and RTPFB types that a re handled in this way include:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="sectio <dl>
n-9.2-20.1.2"> <dt>Temporal-Spatial Trade-off Notification (TSTN):</dt>
<li pn="section-9.2-20.1.2.1"> <dd>(PT=PSFB, FMT=6) <xref target="RFC5104"/>. This message
<dl newline="false" spacing="normal" indent="3" pn="section-9.2-
20.1.2.1.1">
<dt pn="section-9.2-20.1.2.1.1.1">Temporal-Spatial Trade-off N
otification (TSTN):</dt>
<dd pn="section-9.2-20.1.2.1.1.2">(PT=PSFB, FMT=6) <xref targe
t="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>. This
message
is a notification in response to a prior TSTR. is a notification in response to a prior TSTR.
</dd> </dd>
<dt pn="section-9.2-20.1.2.1.1.3">Temporary Maximum Media Stre <dt>Temporary Maximum Media Stream Bit Rate Notification (TMMB
am Bit Rate Notification (TMMBN):</dt> N):</dt>
<dd pn="section-9.2-20.1.2.1.1.4">(PT=RTPFB, FMT=4) <xref targ <dd>(PT=RTPFB, FMT=4) <xref target="RFC5104"/>. This message i
et="RFC5104" format="default" sectionFormat="of" derivedContent="RFC5104"/>. Thi s a
s message is a
notification in response to a prior TMMBR, but it can al so be sent notification in response to a prior TMMBR, but it can al so be sent
unsolicited. unsolicited.
</dd> </dd>
</dl> </dl>
</li> </li>
</ul> </ul>
</li> <ul empty="true">
</ul> <li>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-9.
2-21">
<li pn="section-9.2-21.1">
If the RTCP packet is of type APP, then it is handled in an applic ation-specific If the RTCP packet is of type APP, then it is handled in an applic ation-specific
manner. If the application does not recognize the APP packet, manner. If the application does not recognize the APP packet,
then it <bcp14>MUST</bcp14> be discarded. then it <bcp14>MUST</bcp14> be discarded.
</li> </li>
</ul> </ul>
</section> </section>
<section anchor="sec-rtprtcp-mux" toc="include" numbered="true" removeInRF <section anchor="sec-rtprtcp-mux">
C="false" pn="section-9.3"> <name>RTP/RTCP Multiplexing</name>
<name slugifiedName="name-rtp-rtcp-multiplexing">RTP/RTCP Multiplexing</ <t>
name>
<t indent="0" pn="section-9.3-1">
Within a BUNDLE group, the offerer and answerer <bcp14>MUST</bcp14> en able Within a BUNDLE group, the offerer and answerer <bcp14>MUST</bcp14> en able
RTP/RTCP multiplexing <xref format="default" target="RFC5761" sectionF ormat="of" derivedContent="RFC5761"/> for the RTP-based bundled media (i.e., the RTP/RTCP multiplexing <xref target="RFC5761"/> for the RTP-based bundl ed media (i.e., the
same transport will be used for both RTP packets and RTCP packets). same transport will be used for both RTP packets and RTCP packets).
In addition, the offerer and answerer <bcp14>MUST</bcp14> support the In addition, the offerer and answerer <bcp14>MUST</bcp14> support the
SDP 'rtcp-mux-only' attribute <xref format="default" target="RFC8858" sectionFormat="of" derivedContent="RFC8858"/>. SDP 'rtcp-mux-only' attribute <xref target="RFC8858"/>.
</t> </t>
<section anchor="sec-rtprtcp-mux-oa" toc="include" numbered="true" remov <section anchor="sec-rtprtcp-mux-oa">
eInRFC="false" pn="section-9.3.1"> <name>SDP Offer/Answer Procedures</name>
<name slugifiedName="name-sdp-offer-answer-procedures-2">SDP Offer/Ans <t>
wer Procedures</name>
<t indent="0" pn="section-9.3.1-1">
This section describes how an offerer and answerer use the This section describes how an offerer and answerer use the
SDP 'rtcp-mux' <xref format="default" target="RFC5761" sectionFormat SDP 'rtcp-mux' <xref target="RFC5761"/> and SDP 'rtcp-mux-only' attr
="of" derivedContent="RFC5761"/> and SDP 'rtcp-mux-only' attributes ibutes
<xref format="default" target="RFC8858" sectionFormat="of" derivedCo <xref target="RFC8858"/>
ntent="RFC8858"/>
to negotiate usage of RTP/RTCP multiplexing for RTP-based bundled me dia. to negotiate usage of RTP/RTCP multiplexing for RTP-based bundled me dia.
</t> </t>
<t indent="0" pn="section-9.3.1-2"> <t>
RTP/RTCP multiplexing only applies to RTP-based media. However, as d escribed in RTP/RTCP multiplexing only applies to RTP-based media. However, as d escribed in
<xref format="default" target="sec-sdp-oa-cat" sectionFormat="of" de <xref target="sec-sdp-oa-cat"/>, within an offer
rivedContent="Section 7.1.3"/>, within an offer or answer, the SDP 'rtcp-mux' and SDP 'rtcp-mux-only' attributes mig
or answer the SDP 'rtcp-mux' and SDP 'rtcp-mux-only' attributes migh ht be included in
t be included in a bundled "m=" section for non-RTP-based media (if such an "m=" sect
a bundled "m=" section for non-RTP-based media (if such "m=" section ion is the offerer-tagged
is the offerer-tagged
"m=" section or answerer-tagged "m=" section). "m=" section or answerer-tagged "m=" section).
</t> </t>
<section anchor="sec-rtprtcp-mux-oa-ino" toc="exclude" numbered="true" <section anchor="sec-rtprtcp-mux-oa-ino">
removeInRFC="false" pn="section-9.3.1.1"> <name>Generating the Initial BUNDLE Offer</name>
<name slugifiedName="name-generating-the-initial-bundle-b">Generatin <t>
g the Initial BUNDLE offer</name>
<t indent="0" pn="section-9.3.1.1-1">
When an offerer generates an initial BUNDLE offer, if the offer cont ains When an offerer generates an initial BUNDLE offer, if the offer cont ains
one or more bundled "m=" sections for RTP-based media (or, if there is a chance that "m=" sections one or more bundled "m=" sections for RTP-based media (or if there is a chance that "m=" sections
for RTP-based media will later be added to the BUNDLE group), the of ferer <bcp14>MUST</bcp14> for RTP-based media will later be added to the BUNDLE group), the of ferer <bcp14>MUST</bcp14>
include an SDP 'rtcp-mux' attribute <xref format="default" target="R FC5761" sectionFormat="of" derivedContent="RFC5761"/> in each include an SDP 'rtcp-mux' attribute <xref target="RFC5761"/> in each
bundled "m=" section (excluding any bundle-only "m=" sections). In a ddition, the offerer <bcp14>MAY</bcp14> include an bundled "m=" section (excluding any bundle-only "m=" sections). In a ddition, the offerer <bcp14>MAY</bcp14> include an
SDP 'rtcp-mux-only' attribute <xref format="default" target="RFC8858 " sectionFormat="of" derivedContent="RFC8858"/> SDP 'rtcp-mux-only' attribute <xref target="RFC8858"/>
in one or more bundled "m=" sections for RTP-based media. in one or more bundled "m=" sections for RTP-based media.
</t> </t>
<t indent="0" pn="section-9.3.1.1-2"> <t indent="3">
NOTE: Whether the offerer includes the SDP 'rtcp-mux-only' attribute NOTE: Whether the offerer includes the SDP 'rtcp-mux-only' attribute
depends on whether the offerer supports fallback to usage of a separ ate depends on whether the offerer supports fallback to usage of a separ ate
port for RTCP in case the answerer moves one or more "m=" sections f or RTP-based media port for RTCP in case the answerer moves one or more "m=" sections f or RTP-based media
out of the BUNDLE group in the answer. out of the BUNDLE group in the answer.
</t> </t>
<t indent="0" pn="section-9.3.1.1-3"> <t indent="3">
NOTE: If the offerer includes an SDP 'rtcp-mux' attribute in the bun NOTE: If the offerer includes an SDP 'rtcp-mux' attribute in the bun
dled "m=" sections, dled "m=" sections but does not include an SDP 'rtcp-mux-only' attribute,
but does not include an SDP 'rtcp-mux-only' attribute, the offerer can also include an SDP 'rtcp' attribute <xref target="R
the offerer can also include an SDP 'rtcp' attribute <xref format="d FC3605"/> in one or more RTP-based bundled "m=" sections in order
efault" target="RFC3605" sectionFormat="of" derivedContent="RFC3605"/> in one or to provide a fallback port for RTCP, as described in <xref target="R
more RTP-based bundled "m=" sections in order FC5761"/>. However, the fallback port will only be applied to "m=" sections for
to provide a fallback port for RTCP, as described in <xref format="d RTP-based
efault" target="RFC5761" sectionFormat="of" derivedContent="RFC5761"/>. However,
the fallback port will only be applied to "m=" sections for RTP-based
media that are moved out of the BUNDLE group by the answerer. media that are moved out of the BUNDLE group by the answerer.
</t> </t>
<t indent="0" pn="section-9.3.1.1-4"> <t>
In the initial BUNDLE offer, the address:port combination for RTCP < bcp14>MUST</bcp14> be unique in each In the initial BUNDLE offer, the address:port combination for RTCP < bcp14>MUST</bcp14> be unique in each
bundled "m=" section for RTP-based media (excluding a bundle-only "m =" section), similar to RTP. bundled "m=" section for RTP-based media (excluding a bundle-only "m =" section), similar to RTP.
</t> </t>
</section> </section>
<section anchor="sec-rtprtcp-mux-oa-ans" toc="exclude" numbered="true" <section anchor="sec-rtprtcp-mux-oa-ans">
removeInRFC="false" pn="section-9.3.1.2"> <name>Generating the SDP Answer</name>
<name slugifiedName="name-generating-the-sdp-answer-2">Generating th <t>
e SDP Answer</name> When an answerer generates an answer, if the answerer supports RTP-b
<t indent="0" pn="section-9.3.1.2-1"> ased media
When an answerer generates an answer, if the answerer supports RTP-b
ased media,
and if a bundled "m=" section in the corresponding offer contained a n SDP 'rtcp-mux' attribute, and if a bundled "m=" section in the corresponding offer contained a n SDP 'rtcp-mux' attribute,
the answerer <bcp14>MUST</bcp14> enable usage of RTP/RTCP multiplexi ng, even if there currently the answerer <bcp14>MUST</bcp14> enable usage of RTP/RTCP multiplexi ng, even if there currently
are no bundled "m=" sections for RTP-based media within the BUNDLE g roup. The answerer <bcp14>MUST</bcp14> include are no bundled "m=" sections for RTP-based media within the BUNDLE g roup. The answerer <bcp14>MUST</bcp14> include
an SDP 'rtcp-mux' attribute in the answerer-tagged "m=" section, fol lowing the procedures for an SDP 'rtcp-mux' attribute in the answerer-tagged "m=" section, fol lowing the procedures for
BUNDLE attributes (<xref format="default" target="sec-sdp-oa-cat" se ctionFormat="of" derivedContent="Section 7.1.3"/>). BUNDLE attributes (<xref target="sec-sdp-oa-cat"/>).
In addition, if the "m=" section that is selected as the offerer-tag ged "m=" section contained In addition, if the "m=" section that is selected as the offerer-tag ged "m=" section contained
an SDP 'rtcp-mux-only' attribute, the answerer <bcp14>MUST</bcp14> i nclude an SDP 'rtcp-mux-only' attribute an SDP 'rtcp-mux-only' attribute, the answerer <bcp14>MUST</bcp14> i nclude an SDP 'rtcp-mux-only' attribute
in the answerer-tagged "m=" section. in the answerer-tagged "m=" section.
</t> </t>
<t indent="0" pn="section-9.3.1.2-2"> <t>
In an initial BUNDLE offer, if the suggested offerer-tagged "m=" sec tion contained an In an initial BUNDLE offer, if the suggested offerer-tagged "m=" sec tion contained an
SDP 'rtcp-mux-only' attribute, the "m=" section was for RTP-based me dia. If the SDP 'rtcp-mux-only' attribute, the "m=" section was for RTP-based me dia. If the
answerer does not accept the "m=" section in the created BUNDLE grou answerer does not accept the "m=" section in the created BUNDLE grou
p, and moves the p and moves the
"m=" section out of the BUNDLE group (<xref format="default" target= "m=" section out of the BUNDLE group (<xref target="sec-sdp-oa-ans-m
"sec-sdp-oa-ans-mov" sectionFormat="of" derivedContent="Section 7.3.2"/>), ov"/>),
the answerer <bcp14>MUST</bcp14> include the attribute in the moved "m=" section and enable RTP/RTCP the answerer <bcp14>MUST</bcp14> include the attribute in the moved "m=" section and enable RTP/RTCP
multiplexing for the media associated with the "m=" section. If the answerer rejects the "m=" section multiplexing for the media associated with the "m=" section. If the answerer rejects the "m=" section
(<xref format="default" target="sec-sdp-oa-ans-rej" sectionFormat="o (<xref target="sec-sdp-oa-ans-rej"/>),
f" derivedContent="Section 7.3.3"/>) the answerer <bcp14>MUST NOT</bcp14> include the attribute.
the answerer MUST NOT include the attribute.
</t> </t>
<t indent="0" pn="section-9.3.1.2-3"> <t>
The answerer <bcp14>MUST NOT</bcp14> include an SDP 'rtcp' attribute in any bundled "m=" section The answerer <bcp14>MUST NOT</bcp14> include an SDP 'rtcp' attribute in any bundled "m=" section
in the answer. The answerer will use the port value of the offerer-t agged in the answer. The answerer will use the port value of the offerer-t agged
"m=" section sending RTP and RTCP packets associated with RTP-based bundled media "m=" section sending RTP and RTCP packets associated with RTP-based bundled media
towards the offerer. towards the offerer.
</t> </t>
<t indent="0" pn="section-9.3.1.2-4"> <t>
If the usage of RTP/RTCP multiplexing within a BUNDLE group has been If the usage of RTP/RTCP multiplexing within a BUNDLE group has been
negotiated in a previous offer/answer exchange, the answerer <bcp14> MUST</bcp14> negotiated in a previous offer/answer exchange, the answerer <bcp14> MUST</bcp14>
include an SDP 'rtcp-mux' attribute in the answerer-tagged "m=" sect ion. include an SDP 'rtcp-mux' attribute in the answerer-tagged "m=" sect ion.
It is not possible to disable RTP/RTCP multiplexing within a BUNDLE group. It is not possible to disable RTP/RTCP multiplexing within a BUNDLE group.
</t> </t>
</section> </section>
<section anchor="sec-rtprtcp-mux-oa-pra" toc="exclude" numbered="true" <section anchor="sec-rtprtcp-mux-oa-pra">
removeInRFC="false" pn="section-9.3.1.3"> <name>Offerer Processing of the SDP Answer</name>
<name slugifiedName="name-offerer-processing-of-the-sd">Offerer Proc <t>
essing of the SDP Answer</name>
<t indent="0" pn="section-9.3.1.3-1">
When an offerer receives an answer, if the answerer has accepted When an offerer receives an answer, if the answerer has accepted
the usage of RTP/RTCP multiplexing (<xref target="sec-rtprtcp-mux-oa -ans" format="default" sectionFormat="of" derivedContent="Section 9.3.1.2"/>), the usage of RTP/RTCP multiplexing (<xref target="sec-rtprtcp-mux-oa -ans"/>),
the answerer follows the procedures for RTP/RTCP multiplexing define d the answerer follows the procedures for RTP/RTCP multiplexing define d
in <xref format="default" target="RFC5761" sectionFormat="of" derive dContent="RFC5761"/>. The in <xref target="RFC5761"/>. The
offerer will use the port value of the answerer-tagged "m=" section offerer will use the port value of the answerer-tagged "m=" section
for sending RTP and RTCP packets associated with for sending RTP and RTCP packets associated with
RTP-based bundled media towards the answerer. RTP-based bundled media towards the answerer.
</t> </t>
<t indent="0" pn="section-9.3.1.3-2"> <t indent="3">
NOTE: It is considered a protocol error if the answerer has not NOTE: It is considered a protocol error if the answerer has not
accepted the usage of RTP/RTCP multiplexing for RTP-based "m=" secti ons accepted the usage of RTP/RTCP multiplexing for RTP-based "m=" secti ons
that the answerer included in the BUNDLE group. that the answerer included in the BUNDLE group.
</t> </t>
</section> </section>
<section anchor="sec-rtprtcp-mux-oa-mod" toc="exclude" numbered="true" <section anchor="sec-rtprtcp-mux-oa-mod">
removeInRFC="false" pn="section-9.3.1.4"> <name>Modifying the Session</name>
<name slugifiedName="name-modifying-the-session-2">Modifying the Ses <t>
sion</name>
<t indent="0" pn="section-9.3.1.4-1">
When an offerer generates a subsequent offer, the offerer <bcp14>MUS T</bcp14> include When an offerer generates a subsequent offer, the offerer <bcp14>MUS T</bcp14> include
an SDP 'rtcp-mux' attribute in the offerer-tagged "m=" section, foll owing an SDP 'rtcp-mux' attribute in the offerer-tagged "m=" section, foll owing
the procedures for IDENTICAL multiplexing category attributes in the procedures for IDENTICAL multiplexing category attributes in
<xref format="default" target="sec-sdp-oa-cat" sectionFormat="of" de rivedContent="Section 7.1.3"/>. <xref target="sec-sdp-oa-cat"/>.
</t> </t>
</section> </section>
</section> </section>
</section> </section>
</section> </section>
<section anchor="sec-ice" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-ice">
pn="section-10"> <name>ICE Considerations</name>
<name slugifiedName="name-ice-considerations">ICE Considerations</name> <t>
<t indent="0" pn="section-10-1">
This section describes how to use the BUNDLE grouping extension together This section describes how to use the BUNDLE grouping extension together
with the ICE mechanism <xref format="default" target="RFC8445" sectionFo rmat="of" derivedContent="RFC8445"/>. with the ICE mechanism <xref target="RFC8445"/>.
</t> </t>
<t indent="0" pn="section-10-2"> <t>
The generic procedures for negotiating the usage of ICE using SDP, defin ed The generic procedures for negotiating the usage of ICE using SDP, defin ed
in <xref target="RFC8839" format="default" sectionFormat="of" derivedCon tent="RFC8839"/>, also apply to the usage of ICE in <xref target="RFC8839"/>, also apply to the usage of ICE
with BUNDLE, with the following exceptions: with BUNDLE, with the following exceptions:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-10- <ul>
3"> <li>
<li pn="section-10-3.1">
When the BUNDLE transport has been established, ICE connectivity che cks and keepalives When the BUNDLE transport has been established, ICE connectivity che cks and keepalives
only need to be performed for the BUNDLE transport, instead of per i ndividual bundled "m=" section only need to be performed for the BUNDLE transport, instead of per i ndividual bundled "m=" section
within the BUNDLE group. within the BUNDLE group.
</li> </li>
<li pn="section-10-3.2"> <li>
The generic SDP attribute offer/answer considerations (<xref format= The generic SDP attribute offer/answer considerations (<xref target=
"default" target="sec-sdp-oa-cat" sectionFormat="of" derivedContent="Section 7.1 "sec-sdp-oa-cat"/>) also apply to ICE-related
.3"/>) also apply to ICE-related
attributes. Therefore, when an offerer sends an initial BUNDLE offer (in order to negotiate a BUNDLE group), the offerer attributes. Therefore, when an offerer sends an initial BUNDLE offer (in order to negotiate a BUNDLE group), the offerer
includes ICE-related media-level attributes in each bundled "m=" sec tion (excluding any bundle-only "m=" sections), includes ICE-related media-level attributes in each bundled "m=" sec tion (excluding any bundle-only "m=" sections),
and each "m=" section <bcp14>MUST</bcp14> contain unique ICE propert ies. When an answerer generates an answer (initial BUNDLE answer or subsequent) and each "m=" section <bcp14>MUST</bcp14> contain unique ICE propert ies. When an answerer generates an answer (initial BUNDLE answer or subsequent)
that contains a BUNDLE group, and when an offerer sends a subsequent offer that contains a BUNDLE group, ICE-related media-level that contains a BUNDLE group and when an offerer sends a subsequent offer that contains a BUNDLE group, ICE-related media-level
attributes are only included in the tagged "m=" section (suggested o fferer-tagged "m=" section or answerer-tagged "m=" section), and attributes are only included in the tagged "m=" section (suggested o fferer-tagged "m=" section or answerer-tagged "m=" section), and
the ICE properties are applied to each bundled "m=" section within t he BUNDLE group. the ICE properties are applied to each bundled "m=" section within t he BUNDLE group.
</li> </li>
</ul> </ul>
<t indent="0" pn="section-10-4"> <t indent="3">
NOTE: Most ICE-related media-level SDP attributes belong to the TRANSPOR T multiplexing category NOTE: Most ICE-related media-level SDP attributes belong to the TRANSPOR T multiplexing category
<xref target="RFC8859" format="default" sectionFormat="of" derivedConten t="RFC8859"/>, and the generic SDP attribute offer/answer <xref target="RFC8859"/>, and the generic SDP attribute offer/answer
considerations for the TRANSPORT multiplexing category apply to the attr ibutes. However, in the case of considerations for the TRANSPORT multiplexing category apply to the attr ibutes. However, in the case of
ICE-related attributes, the same considerations also apply to ICE-relate d media-level attributes that ICE-related attributes, the same considerations also apply to ICE-relate d media-level attributes that
belong to other multiplexing categories. belong to other multiplexing categories.
</t> </t>
<t indent="0" pn="section-10-5"> <t indent="3">
NOTE: The following ICE-related media-level SDP attributes are defined i n NOTE: The following ICE-related media-level SDP attributes are defined i n
<xref target="RFC8839" format="default" sectionFormat="of" derivedConten t="RFC8839"/>: 'candidate', 'remote-candidates', 'ice-mismatch', <xref target="RFC8839"/>: 'candidate', 'remote-candidates', 'ice-mismatc h',
'ice-ufrag', 'ice-pwd', and 'ice-pacing'. 'ice-ufrag', 'ice-pwd', and 'ice-pacing'.
</t> </t>
<t indent="0" pn="section-10-6"> <t>
Initially, before ICE has produced selected candidate pairs that will be used for media, there might Initially, before ICE has produced selected candidate pairs that will be used for media, there might
be multiple transports established (if multiple candidate pairs are test ed). Once ICE has selected be multiple transports established (if multiple candidate pairs are test ed). Once ICE has selected
candidate pairs, they form the BUNDLE transport. candidate pairs, they form the BUNDLE transport.
</t> </t>
<t indent="0" pn="section-10-7"> <t>
Support and usage of the ICE mechanism together with the BUNDLE extensio n Support and usage of the ICE mechanism together with the BUNDLE extensio n
is <bcp14>OPTIONAL</bcp14>, and the procedures in this section only appl y when the is <bcp14>OPTIONAL</bcp14>, and the procedures in this section only appl y when the
ICE mechanism is used. Note that applications might mandate usage ICE mechanism is used. Note that applications might mandate usage
of the ICE mechanism even if the BUNDLE extension is not used. of the ICE mechanism even if the BUNDLE extension is not used.
</t> </t>
<t indent="0" pn="section-10-8"> <t indent="3">
NOTE: If the Trickle ICE mechanism <xref target="RFC8840" format="defaul NOTE: If the Trickle ICE mechanism <xref target="RFC8840"/>
t" sectionFormat="of" derivedContent="RFC8840"/>
is used, an offerer and answerer might assign a port value of '9' and an IPv4 is used, an offerer and answerer might assign a port value of '9' and an IPv4
address of '0.0.0.0' (or, the IPv6 equivalent '::') to multiple bundled "m=" sections address of '0.0.0.0' (or, the IPv6 equivalent '::') to multiple bundled "m=" sections
in the initial BUNDLE offer. The offerer and answerer will follow the no rmal procedures in the initial BUNDLE offer. The offerer and answerer will follow the no rmal procedures
for generating the offers and answers, including picking a bundled "m=" section as the for generating the offers and answers, including picking a bundled "m=" section as the
suggested offerer-tagged "m=" section, selecting the tagged "m=" section s, etc. The only suggested offerer-tagged "m=" section, selecting the tagged "m=" section s, etc. The only
difference is that media cannot be sent until one or more candidates hav e been provided. difference is that media cannot be sent until one or more candidates hav e been provided.
Once a BUNDLE group has been negotiated, trickled candidates associated with a bundled Once a BUNDLE group has been negotiated, trickled candidates associated with a bundled
"m=" section will be applied to all bundled "m=" sections within the BUN DLE group. "m=" section will be applied to all bundled "m=" sections within the BUN DLE group.
</t> </t>
</section> </section>
<section anchor="sec-dtls" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-dtls">
pn="section-11"> <name>DTLS Considerations</name>
<name slugifiedName="name-dtls-considerations">DTLS Considerations</name> <t>
<t indent="0" pn="section-11-1">
One or more media streams within a BUNDLE group might use One or more media streams within a BUNDLE group might use
the Datagram Transport Layer Security (DTLS) protocol the DTLS protocol
<xref format="default" target="RFC6347" sectionFormat="of" derivedConten <xref target="RFC6347"/>
t="RFC6347"/>
in order to encrypt the data or negotiate encryption keys in order to encrypt the data or negotiate encryption keys
if another encryption mechanism is used to encrypt media. if another encryption mechanism is used to encrypt media.
</t> </t>
<t indent="0" pn="section-11-2"> <t>
When DTLS is used within a BUNDLE group, the following rules When DTLS is used within a BUNDLE group, the following rules
apply: apply:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-11- <ul>
3"> <li>
<li pn="section-11-3.1">
There can only be one DTLS association There can only be one DTLS association
<xref format="default" target="RFC6347" sectionFormat="of" derivedCont ent="RFC6347"/> <xref target="RFC6347"/>
associated with the BUNDLE group; associated with the BUNDLE group;
</li> </li>
<li pn="section-11-3.2"> <li>
Each usage of the DTLS association within the BUNDLE Each usage of the DTLS association within the BUNDLE
group <bcp14>MUST</bcp14> use the same mechanism for determining group <bcp14>MUST</bcp14> use the same mechanism for determining
which endpoints (the offerer or answerer) become which endpoints (the offerer or answerer) become
DTLS client and DTLS server; DTLS client and DTLS server;
</li> </li>
<li pn="section-11-3.3"> <li>
Each usage of the DTLS association within the BUNDLE Each usage of the DTLS association within the BUNDLE
group <bcp14>MUST</bcp14> use the same mechanism for determining group <bcp14>MUST</bcp14> use the same mechanism for determining
whether an offer or answer will trigger the whether an offer or answer will trigger the
establishment of a new DTLS association or establishment of a new DTLS association or if
an existing DTLS association will be used; and an existing DTLS association will be used instead; and
</li> </li>
<li pn="section-11-3.4"> <li>
If the DTLS client supports DTLS-SRTP, If the DTLS client supports DTLS-SRTP,
it <bcp14>MUST</bcp14> include the 'use_srtp' extension it <bcp14>MUST</bcp14> include the 'use_srtp' extension
in the DTLS ClientHello message in the DTLS ClientHello message
<xref format="default" target="RFC5764" sectionFormat="of" derivedCont ent="RFC5764"/>. <xref target="RFC5764"/>.
The client <bcp14>MUST</bcp14> include the extension even if the usage The client <bcp14>MUST</bcp14> include the extension even if the usage
of DTLS-SRTP is not negotiated as part of the of DTLS-SRTP is not negotiated as part of the
multimedia session (e.g., the SIP session <xref format="default" targe t="RFC3261" sectionFormat="of" derivedContent="RFC3261"/>). multimedia session (e.g., the SIP session <xref target="RFC3261"/>).
</li> </li>
</ul> </ul>
<t indent="0" pn="section-11-4"> <t indent="3">
NOTE: The inclusion of the 'use_srtp' extension during the initial NOTE: The inclusion of the 'use_srtp' extension during the initial
DTLS handshake ensures that a DTLS renegotiation will not be required DTLS handshake ensures that a DTLS renegotiation will not be required
in order to include the extension, in case DTLS-SRTP encrypted media in order to include the extension in case DTLS-SRTP encrypted media
is added to the BUNDLE group later during the multimedia session. is added to the BUNDLE group later during the multimedia session.
</t> </t>
</section> </section>
<section anchor="sec-extmap" toc="include" numbered="true" removeInRFC="fals <section anchor="sec-extmap">
e" pn="section-12"> <name>RTP Header Extensions Consideration</name>
<name slugifiedName="name-rtp-header-extensions-consi">RTP Header Extensio <t>When RTP header extensions <xref target="RFC8285"/> are used in the con
ns Consideration</name> text of this
<t indent="0" pn="section-12-1">When RTP header extensions <xref target="R
FC8285" format="default" sectionFormat="of" derivedContent="RFC8285"/> are used
in the context of this
specification, the identifier used for a given extension <bcp14>MUST</bcp 14> identify the same specification, the identifier used for a given extension <bcp14>MUST</bcp 14> identify the same
extension across all the bundled media descriptions. </t> extension across all the bundled media descriptions. </t>
</section> </section>
<section anchor="sec-3264" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-3264">
pn="section-13"> <name>Updates to RFC 3264</name>
<name slugifiedName="name-update-to-rfc-3264">Update to RFC 3264</name> <t>
<t indent="0" pn="section-13-1"> This section updates <xref target="RFC3264"/> in order to allow extensio
This section updates RFC 3264, in order to allow extensions to define th ns to define the usage of
e usage of
a zero port value in offers and answers for purposes other than removing or disabling a zero port value in offers and answers for purposes other than removing or disabling
media streams. The following sections are being updated: media streams. The following sections are being updated:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-13- <ul>
2"> <li>"Unicast Streams"; see <xref target="RFC3264" section="5.1"/>.</li>
<li pn="section-13-2.1">"Unicast Streams"; see <xref target="RFC3264" se <li>"Putting a Unicast Media Stream on Hold"; see <xref target="RFC3264"
ctionFormat="of" section="5.1" format="default" derivedLink="https://rfc-editor. section="8.4"/>. </li>
org/rfc/rfc3264#section-5.1" derivedContent="RFC3264"/></li>
<li pn="section-13-2.2">"Putting a Unicast Media Stream on Hold"; see <x
ref target="RFC3264" sectionFormat="of" section="8.4" format="default" derivedLi
nk="https://rfc-editor.org/rfc/rfc3264#section-8.4" derivedContent="RFC3264"/>.
</li>
</ul> </ul>
<section anchor="sec-3264-old-5_1" toc="include" numbered="true" removeInR <section anchor="sec-3264-old-5_1">
FC="false" pn="section-13.1"> <name>Original Text from RFC 3264, Section 5.1, Paragraph 2</name>
<name slugifiedName="name-original-text-from-rfc-3264">Original Text fro <blockquote>
m RFC 3264, Section 5.1, 2nd Paragraph</name>
<blockquote pn="section-13.1-1">
For recvonly and sendrecv streams, the port number and address in the For recvonly and sendrecv streams, the port number and address in the
offer indicate where the offerer would like to receive the media offer indicate where the offerer would like to receive the media
stream. For sendonly RTP streams, the address and port number stream. For sendonly RTP streams, the address and port number
indirectly indicate where the offerer wants to receive RTCP reports. indirectly indicate where the offerer wants to receive RTCP reports.
Unless there is an explicit indication otherwise, reports are sent to Unless there is an explicit indication otherwise, reports are sent to
the port number one higher than the number indicated. The IP address the port number one higher than the number indicated. The IP address
and port present in the offer indicate nothing about the source IP and port present in the offer indicate nothing about the source IP
address and source port of RTP and RTCP packets that will be sent by address and source port of RTP and RTCP packets that will be sent by
the offerer. A port number of zero in the offer indicates that the the offerer. A port number of zero in the offer indicates that the
stream is offered but <bcp14>MUST NOT</bcp14> be used. This has no usef ul semantics stream is offered but <bcp14>MUST NOT</bcp14> be used. This has no usef ul semantics
in an initial offer, but is allowed for reasons of completeness, in an initial offer, but is allowed for reasons of completeness,
since the answer can contain a zero port indicating a rejected stream since the answer can contain a zero port indicating a rejected stream
(Section 6). Furthermore, existing streams can be terminated by (Section <xref target="RFC3264" sectionFormat="bare" section="6"/>). Fur
setting the port to zero (Section 8). In general, a port number of thermore, existing streams can be terminated by
setting the port to zero (Section <xref target="RFC3264" sectionFormat="
bare" section="8"/>). In general, a port number of
zero indicates that the media stream is not wanted. zero indicates that the media stream is not wanted.
</blockquote> </blockquote>
</section> </section>
<section anchor="sec-3264-new-5_1" toc="include" numbered="true" removeInR <section anchor="sec-3264-new-5_1">
FC="false" pn="section-13.2"> <name>New Text Replacing RFC 3264, Section 5.1, Paragraph 2</name>
<name slugifiedName="name-new-text-replacing-rfc-3264">New Text Replacin <blockquote><t>
g RFC 3264, Section 5.1, 2nd Paragraph</name>
<t indent="0" pn="section-13.2-1">
For recvonly and sendrecv streams, the port number and address in the For recvonly and sendrecv streams, the port number and address in the
offer indicate where the offerer would like to receive the media offer indicate where the offerer would like to receive the media
stream. For sendonly RTP streams, the address and port number stream. For sendonly RTP streams, the address and port number
indirectly indicate where the offerer wants to receive RTCP reports. indirectly indicate where the offerer wants to receive RTCP reports.
Unless there is an explicit indication otherwise, reports are sent to Unless there is an explicit indication otherwise, reports are sent to
the port number one higher than the number indicated. The IP address the port number one higher than the number indicated. The IP address
and port present in the offer indicate nothing about the source IP and port present in the offer indicate nothing about the source IP
address and source port of the RTP and RTCP packets that will be sent by address and source port of the RTP and RTCP packets that will be sent by
the offerer. By default, a port number of zero in the offer indicates th at the the offerer. By default, a port number of zero in the offer indicates th at the
stream is offered but <bcp14>MUST NOT</bcp14> be used, but an extension mechanism stream is offered but <bcp14>MUST NOT</bcp14> be used, but an extension mechanism
might specify different semantics for the usage of a zero port value. might specify different semantics for the usage of a zero port value.
Furthermore, existing streams can be terminated by setting the port to Furthermore, existing streams can be terminated by setting the port to
zero (Section 8). In general, a port number of zero by default indicates zero (Section <xref target="RFC3264" sectionFormat="bare" section="8"/>) . In general, a port number of zero by default indicates
that the media stream is not wanted. that the media stream is not wanted.
</t> </t></blockquote>
</section> </section>
<section anchor="sec-3264-old-8_4" toc="include" numbered="true" removeInR <section anchor="sec-3264-old-8_4">
FC="false" pn="section-13.3"> <name>Original Text from RFC 3264, Section 8.4, Paragraph 6</name>
<name slugifiedName="name-original-text-from-rfc-3264-">Original Text fr <blockquote>RFC 2543 [10] specified that placing a user on hold was acco
om RFC 3264, Section 8.4, 6th Paragraph</name> mplished
<blockquote pn="section-13.3-1">RFC 2543 [10] specified that placing a u
ser on hold was accomplished
by setting the connection address to 0.0.0.0. Its usage for putting by setting the connection address to 0.0.0.0. Its usage for putting
a call on hold is no longer recommended, since it doesn't allow for a call on hold is no longer recommended, since it doesn't allow for
RTCP to be used with held streams, doesn't work with IPv6, and breaks RTCP to be used with held streams, doesn't work with IPv6, and breaks
with connection oriented media. However, it can be useful in an with connection oriented media. However, it can be useful in an
initial offer when the offerer knows it wants to use a particular set initial offer when the offerer knows it wants to use a particular set
of media streams and formats, but doesn't know the addresses and of media streams and formats, but doesn't know the addresses and
ports at the time of the offer. Of course, when used, the port ports at the time of the offer. Of course, when used, the port
number <bcp14>MUST NOT</bcp14> be zero, which would specify that the stream h as been number <bcp14>MUST NOT</bcp14> be zero, which would specify that the stream h as been
disabled. An agent <bcp14>MUST</bcp14> be capable of receiving SDP with a disabled. An agent <bcp14>MUST</bcp14> be capable of receiving SDP with a
connection address of 0.0.0.0, in which case it means that neither connection address of 0.0.0.0, in which case it means that neither
RTP nor RTCP should be sent to the peer. RTP nor RTCP should be sent to the peer.
</blockquote> </blockquote>
</section> </section>
<section anchor="sec-3264-new-8_4" toc="include" numbered="true" removeInR <section anchor="sec-3264-new-8_4">
FC="false" pn="section-13.4"> <name>New Text Replacing RFC 3264, Section 8.4, Paragraph 6</name>
<name slugifiedName="name-new-text-replacing-rfc-3264-">New Text Replaci <blockquote><t> RFC 2543 <xref target="RFC2543"/> specifies
ng RFC 3264, Section 8.4, 6th Paragraph</name> that placing a user on hold was accomplished by setting the
<t indent="0" pn="section-13.4-1"> connection address to 0.0.0.0. Its usage for putting a call
RFC 2543 <xref target="RFC2543" format="default" sectionFormat="of" deri on hold is no longer recommended, since it doesn't allow for
vedContent="RFC2543"/> specifies that placing a user on hold was accomplished RTCP to be used with held streams, doesn't work with IPv6, and
by setting the connection address to 0.0.0.0. Its usage for putting breaks with connection oriented media. However, it can be
a call on hold is no longer recommended, since it doesn't allow for useful in an initial offer when the offerer knows it wants to
RTCP to be used with held streams, doesn't work with IPv6, and breaks use a particular set of media streams and formats, but doesn't
with connection oriented media. However, it can be useful in an know the addresses and ports at the time of the offer. Of
initial offer when the offerer knows it wants to use a particular set course, when used, the port number <bcp14>MUST NOT</bcp14> be
of media streams and formats, but doesn't know the addresses and zero, if it would specify that the stream has been
ports at the time of the offer. Of course, when used, the port disabled. However, an extension mechanism might specify
number <bcp14>MUST NOT</bcp14> be zero, if it would specify that the str different semantics of the zero port number usage. An agent
eam has been <bcp14>MUST</bcp14> be capable of receiving SDP with a
disabled. However, an extension mechanism might specify different connection address of 0.0.0.0, in which case it means that
semantics of the zero port number usage. An agent <bcp14>MUST</bcp14> be neither RTP nor RTCP is to be sent to the peer.
capable </t></blockquote>
of receiving SDP with a connection address of 0.0.0.0, in which case it
means that neither RTP nor RTCP is to be sent to the peer.
</t>
</section> </section>
</section> </section>
<section anchor="sec-5888" toc="include" numbered="true" removeInRFC="false" <section anchor="sec-5888">
pn="section-14"> <name>Update to RFC 5888</name>
<name slugifiedName="name-update-to-rfc-5888">Update to RFC 5888</name> <t>
<t indent="0" pn="section-14-1"> This section updates RFC 5888 <xref target="RFC5888"/>
This section updates RFC 5888 <xref format="default" target="RFC5888" se
ctionFormat="of" derivedContent="RFC5888"/>,
in order for extensions to allow an SDP 'group' attribute containing in order for extensions to allow an SDP 'group' attribute containing
an identification-tag that identifies an "m=" section with the port set to zero. an identification-tag that identifies an "m=" section with the port set to zero.
"Group Value in Answers" (<xref target="RFC5888" sectionFormat="of" sect ion="9.2" format="default" derivedLink="https://rfc-editor.org/rfc/rfc5888#secti on-9.2" derivedContent="RFC5888"/>) "Group Value in Answers" (<xref target="RFC5888" section="9.2"/>)
is updated. is updated.
</t> </t>
<section anchor="sec-5888-old-9_2" toc="include" numbered="true" removeInR <section anchor="sec-5888-old-9_2">
FC="false" pn="section-14.1"> <name>Original Text from RFC 5888, Section 9.2, Paragraph 3</name>
<name slugifiedName="name-original-text-from-rfc-5888">Original Text fro <blockquote>SIP entities refuse media streams by setting the port to zer
m RFC 5888, Section 9.2, 3rd Paragraph</name> o in the corresponding
<blockquote pn="section-14.1-1">SIP entities refuse media streams by set
ting the port to zero in the corresponding
"m" line. "a=group" lines <bcp14>MUST NOT</bcp14> contain identification -tags that correspond to "m" line. "a=group" lines <bcp14>MUST NOT</bcp14> contain identification -tags that correspond to
"m" lines with the port set to zero.</blockquote> "m" lines with the port set to zero.</blockquote>
</section> </section>
<section anchor="sec-5888-new-9_2" toc="include" numbered="true" removeInR <section anchor="sec-5888-new-9_2">
FC="false" pn="section-14.2"> <name>New Text Replacing RFC 5888, Section 9.2, Paragraph 3</name>
<name slugifiedName="name-new-text-replacing-rfc-5888">New Text Replacin <blockquote><t> SIP entities refuse media streams by setting
g RFC 5888, Section 9.2, 3rd Paragraph</name> the port to zero in the corresponding "m" line. "a=group"
<t indent="0" pn="section-14.2-1"> lines <bcp14>MUST NOT</bcp14> contain identification-tags that
SIP entities refuse media streams by setting the port to zero in the cor correspond to "m" lines with the port set to zero, but an
responding extension mechanism might specify different semantics for
"m" line. "a=group" lines <bcp14>MUST NOT</bcp14> contain identification including identification-tags that correspond to such "m="
-tags that correspond to lines. </t></blockquote>
"m" lines with the port set to zero, but an extension mechanism might sp
ecify different
semantics for including identification-tags that correspond to such "m="
lines.
</t>
</section> </section>
</section> </section>
<section anchor="sec-receiver-id" toc="include" numbered="true" removeInRFC= <section anchor="sec-receiver-id">
"false" pn="section-15"> <name>RTP/RTCP Extensions for identification-tag Transport</name>
<name slugifiedName="name-rtp-rtcp-extensions-for-ide">RTP/RTCP Extensions <t>
for identification-tag Transport</name> Offerers and answerers <xref target="RFC3264"/> can associate
<t indent="0" pn="section-15-1"> identification-tags with "m=" sections within offers and
Offerers and answerers <xref format="default" target="RFC3264" sectionFo answers using the procedures in <xref
rmat="of" derivedContent="RFC3264"/> target="RFC5888"/>. Each identification-tag uniquely
can associate identification-tags with "m=" sections within offers represents an "m=" section.
and answers, using the procedures in <xref format="default" target="RFC5
888" sectionFormat="of" derivedContent="RFC5888"/>. Each identification-tag uniq
uely represents an "m=" section.
</t> </t>
<t indent="0" pn="section-15-2"> <t>
This section defines a new RTCP SDES item <xref format="default" target= This section defines a new RTCP SDES item <xref target="RFC3550"/>, 'MID
"RFC3550" sectionFormat="of" derivedContent="RFC3550"/>, 'MID', which is used to ', which is used to carry identification-tags within RTCP
carry identification-tags within RTCP
SDES packets. This section also defines a new RTP SDES header extension SDES packets. This section also defines a new RTP SDES header extension
<xref format="default" target="RFC7941" sectionFormat="of" derivedConten t="RFC7941"/>, which <xref target="RFC7941"/>, which
is used to carry the 'MID' RTCP SDES item in RTP packets. is used to carry the 'MID' RTCP SDES item in RTP packets.
</t> </t>
<t indent="0" pn="section-15-3"> <t>
The SDES item and RTP SDES header extension make it possible for a recei ver to associate The SDES item and RTP SDES header extension make it possible for a recei ver to associate
each RTP stream with a specific "m=" section, with which the receiver ha s each RTP stream with a specific "m=" section with which the receiver has
associated an identification-tag, even if those "m=" sections are part o f the same RTP session. associated an identification-tag, even if those "m=" sections are part o f the same RTP session.
The RTP SDES header extension also ensures that the media recipient gets the identification-tag The RTP SDES header extension also ensures that the media recipient gets the identification-tag
upon receipt of the first decodable media and is able to associate the m edia with the upon receipt of the first decodable media and is able to associate the m edia with the
correct application. correct application.
</t> </t>
<t indent="0" pn="section-15-4"> <t>
A media recipient informs the media sender about the identification-tag A media recipient informs the media sender about the identification-tag
associated with an "m=" section through the use of a 'mid' attribute associated with an "m=" section through the use of a 'mid' attribute
<xref format="default" target="RFC5888" sectionFormat="of" derivedConten t="RFC5888"/>. The media sender then <xref target="RFC5888"/>. The media sender then
inserts the identification-tag in RTCP and RTP packets sent to the media recipient. inserts the identification-tag in RTCP and RTP packets sent to the media recipient.
</t> </t>
<t indent="0" pn="section-15-5"> <t indent="3">
NOTE: The text above defines how identification-tags are carried in offe rs NOTE: The text above defines how identification-tags are carried in offe rs
and answers. The usage of other signaling protocols for carrying identif ication-tags and answers. The usage of other signaling protocols for carrying identif ication-tags
is not prevented, but the usage of such protocols is outside the scope o f this document. is not prevented, but the usage of such protocols is outside the scope o f this document.
</t> </t>
<t indent="0" pn="section-15-6"> <t>
<xref format="default" target="RFC3550" sectionFormat="of" derivedConten <xref target="RFC3550"/> defines general procedures
t="RFC3550"/> defines general procedures
regarding the RTCP transmission interval. The RTCP MID SDES item <bcp14> SHOULD</bcp14> be sent in regarding the RTCP transmission interval. The RTCP MID SDES item <bcp14> SHOULD</bcp14> be sent in
the first few RTCP packets after joining the session and <bcp14>SHOULD</ bcp14> be sent regularly the first few RTCP packets after joining the session and <bcp14>SHOULD</ bcp14> be sent regularly
thereafter. The exact number of RTCP packets in which this SDES item is sent is thereafter. The exact number of RTCP packets in which this SDES item is sent is
intentionally not specified here, as it will depend on the expected pack et-loss intentionally not specified here, as it will depend on the expected pack et-loss
rate, the RTCP reporting interval, and the allowable overhead. rate, the RTCP reporting interval, and the allowable overhead.
</t> </t>
<t indent="0" pn="section-15-7"> <t>
The RTP SDES header extension for carrying the 'MID' RTCP SDES <bcp14>SH OULD</bcp14> be included The RTP SDES header extension for carrying the 'MID' RTCP SDES <bcp14>SH OULD</bcp14> be included
in some RTP packets at the start of the session and whenever the SSRC ch anges. It might in some RTP packets at the start of the session and whenever the SSRC ch anges. It might
also be useful to include the header extension in RTP packets that compr ise access points in the media also be useful to include the header extension in RTP packets that compr ise access points in the media
(e.g., with video I-frames). The exact number of RTP packets in which th is header (e.g., with video I-frames). The exact number of RTP packets in which th is header
extension is sent is intentionally not specified here, as it will depend on expected extension is sent is intentionally not specified here, as it will depend on expected
packet-loss rate and loss patterns, the overhead the application can tol erate, and packet-loss rate and loss patterns, the overhead the application can tol erate, and
the importance of immediate receipt of the identification-tag. the importance of immediate receipt of the identification-tag.
</t> </t>
<t indent="0" pn="section-15-8"> <t>
For robustness, endpoints need to be prepared for situations where the For robustness, endpoints need to be prepared for situations where the
reception of the identification-tag is delayed and <bcp14>SHOULD NOT</bc p14> terminate sessions reception of the identification-tag is delayed and <bcp14>SHOULD NOT</bc p14> terminate sessions
in such cases, as the identification-tag is likely to arrive soon. in such cases, as the identification-tag is likely to arrive soon.
</t> </t>
<section anchor="sec-receiver-id-sdes-item" toc="include" numbered="true" <section anchor="sec-receiver-id-sdes-item">
removeInRFC="false" pn="section-15.1"> <name>RTCP MID SDES Item</name>
<name slugifiedName="name-rtcp-mid-sdes-item">RTCP MID SDES Item</name> <artwork name="" type="" alt="">
<artwork align="left" name="" type="" alt="" pn="section-15.1-1">
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MID=15 | length | identification-tag ... | MID=15 | length | identification-tag ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork> </artwork>
<t indent="0" pn="section-15.1-2"> <t>
The identification-tag payload is UTF-8 encoded <xref format="default" The identification-tag payload is UTF-8 encoded <xref target="RFC3629"
target="RFC3629" sectionFormat="of" derivedContent="RFC3629"/>, as in SDP. />, as in SDP.
</t> </t>
<t indent="0" pn="section-15.1-3"> <t>
The identification-tag is not zero terminated. The identification-tag is not zero terminated.
</t> </t>
</section> </section>
<section anchor="sec-receiver-id-rtp-he" toc="include" numbered="true" rem <section anchor="sec-receiver-id-rtp-he">
oveInRFC="false" pn="section-15.2"> <name>RTP SDES Header Extension for MID</name>
<name slugifiedName="name-rtp-sdes-header-extension-f">RTP SDES Header E <t>
xtension For MID</name>
<t indent="0" pn="section-15.2-1">
The payload, containing the identification-tag, of the RTP SDES header extension element The payload, containing the identification-tag, of the RTP SDES header extension element
can be encoded using either the 1-byte or the 2-byte header <xref form at="default" target="RFC7941" sectionFormat="of" derivedContent="RFC7941"/>. The identification-tag payload is UTF-8 can be encoded using either the 1-byte or the 2-byte header <xref targ et="RFC7941"/>. The identification-tag payload is UTF-8
encoded, as in SDP. encoded, as in SDP.
</t> </t>
<t indent="0" pn="section-15.2-2"> <t>
The identification-tag is not zero terminated. Note that the set of he ader extensions The identification-tag is not zero terminated. Note that the set of he ader extensions
included in the packet needs to be padded to the next 32-bit boundary using zero included in the packet needs to be padded to the next 32-bit boundary using zero
bytes <xref format="default" target="RFC8285" sectionFormat="of" deriv edContent="RFC8285"/>. bytes <xref target="RFC8285"/>.
</t> </t>
<t indent="0" pn="section-15.2-3"> <t>
As the identification-tag is included in an RTCP SDES item, an RTP SDE S header As the identification-tag is included in an RTCP SDES item, an RTP SDE S header
extension, or both, there needs to be some consideration about the pac ket expansion extension, or both, there needs to be some consideration about the pac ket expansion
caused by the identification-tag. To avoid Maximum Transmission Unit ( MTU) issues caused by the identification-tag. To avoid Maximum Transmission Unit ( MTU) issues
for the RTP packets, the header extension's size needs to be taken int o account when for the RTP packets, the header extension's size needs to be taken int o account when
encoding the media. encoding the media.
</t> </t>
<t indent="0" pn="section-15.2-4"> <t>
It is recommended that the identification-tag be kept short. Due to th e properties of It is recommended that the identification-tag be kept short. Due to th e properties of
the RTP header extension mechanism, when using the 1-byte header, a ta g that is 1-3 bytes the RTP header extension mechanism, when using the 1-byte header, a ta g that is 1-3 bytes
will result in a minimal number of 32-bit words used for the RTP SDES header extension, will result in a minimal number of 32-bit words used for the RTP SDES header extension,
in case no other header extensions are included at the same time. Note , do take into in case no other header extensions are included at the same time. Note : do take into
account that some single characters when UTF-8 encoded will result in multiple octets. account that some single characters when UTF-8 encoded will result in multiple octets.
The identification-tag <bcp14>MUST NOT</bcp14> contain any user inform ation, and applications <bcp14>SHALL</bcp14> avoid The identification-tag <bcp14>MUST NOT</bcp14> contain any user inform ation, and applications <bcp14>SHALL</bcp14> avoid
generating the identification-tag using a pattern that enables user or application generating the identification-tag using a pattern that enables user or application
identification. identification.
</t> </t>
</section> </section>
</section> </section>
<section anchor="sec-receiver-id-iana" toc="include" numbered="true" removeI <section anchor="sec-receiver-id-iana">
nRFC="false" pn="section-16"> <name>IANA Considerations</name>
<name slugifiedName="name-iana-considerations">IANA Considerations</name> <t>NOTE: Apart from the references, the IANA considerations in this sectio
<section anchor="sec-receiver-id-iana-sdes-item" toc="include" numbered="t n are identical to those in <xref target="RFC8843"/>.</t>
rue" removeInRFC="false" pn="section-16.1"> <section anchor="sec-receiver-id-iana-sdes-item">
<name slugifiedName="name-new-sdes-item">New SDES Item</name> <name>SDES Item</name>
<t indent="0" pn="section-16.1-1"> <t>
This document updates the MID SDES item to the IANA "RTP SDES Item This document updates the MID SDES entry in the "RTP SDES Item
Types" registry as follows: Types" registry as follows:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-16 <dl spacing="compact">
.1-2"> <dt>Value:</dt>
<li pn="section-16.1-2.1"> <dd>15</dd>
<dl newline="false" spacing="normal" indent="3" pn="section-16.1-2.1 <dt>Abbrev.:</dt>
.1"> <dd>MID</dd>
<dt pn="section-16.1-2.1.1.1">Value:</dt> <dt>Name:</dt>
<dd pn="section-16.1-2.1.1.2">15</dd> <dd>Media Identification</dd>
<dt pn="section-16.1-2.1.1.3">Abbrev.:</dt> <dt>Reference:</dt>
<dd pn="section-16.1-2.1.1.4">MID</dd> <dd>RFC 9143</dd>
<dt pn="section-16.1-2.1.1.5">Name:</dt>
<dd pn="section-16.1-2.1.1.6">Media Identification</dd>
<dt pn="section-16.1-2.1.1.7">Reference:</dt>
<dd pn="section-16.1-2.1.1.8">RFC XXXX</dd>
</dl> </dl>
</li>
</ul>
</section> </section>
<section anchor="sec-receiver-id-iana-rtp-uri" toc="include" numbered="tru <section anchor="sec-receiver-id-iana-rtp-uri">
e" removeInRFC="false" pn="section-16.2"> <name>RTP SDES Header Extension URI</name>
<name slugifiedName="name-new-rtp-sdes-header-extensi">New RTP SDES Head <t>
er Extension URI</name> This document updates the extension URI in the "RTP SDES
<t indent="0" pn="section-16.2-1"> Compact Header Extensions" subregistry of the "RTP Compact
This document updates the extension URI in the RTP SDES Compact Header E Header Extensions" sub-registry, according to the
xtensions following data:
sub-registry of the RTP Compact Header Extensions registry sub-registry,
according
to the following data:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-16 <dl spacing="compact">
.2-2"> <dt>Extension URI:</dt>
<li pn="section-16.2-2.1"> <dd>urn:ietf:params:rtp-hdrext:sdes:mid</dd>
<dl newline="false" spacing="normal" indent="3" pn="section-16.2-2.1 <dt>Description:</dt>
.1"> <dd>Media identification</dd>
<dt pn="section-16.2-2.1.1.1">Extension URI:</dt> <dt>Contact:</dt>
<dd pn="section-16.2-2.1.1.2">urn:ietf:params:rtp-hdrext:sdes:mid< <dd>IESG (iesg@ietf.org)</dd>
/dd> <dt>Reference:</dt>
<dt pn="section-16.2-2.1.1.3">Description:</dt> <dd>RFC 9143</dd>
<dd pn="section-16.2-2.1.1.4">Media identification</dd>
<dt pn="section-16.2-2.1.1.5">Contact:</dt>
<dd pn="section-16.2-2.1.1.6">IESG (iesg@ietf.org)</dd>
<dt pn="section-16.2-2.1.1.7">Reference:</dt>
<dd pn="section-16.2-2.1.1.8">RFC XXXX</dd>
</dl> </dl>
</li> <t>
</ul>
<t indent="0" pn="section-16.2-3">
The SDES item does not reveal privacy information about the users. The SDES item does not reveal privacy information about the users.
It is simply used to associate RTP-based media with the correct SDP It is simply used to associate RTP-based media with the correct SDP
media description ("m=" section) in the SDP used to negotiate the media description ("m=" section) in the SDP used to negotiate the
media.</t> media.</t>
<t indent="0" pn="section-16.2-4"> The purpose of the extension is for t he offerer to be able to <t> The purpose of the extension is for the offerer to be able to
associate received multiplexed RTP-based media before the offerer associate received multiplexed RTP-based media before the offerer
receives the associated answer.</t> receives the associated answer.</t>
</section> </section>
<section anchor="sec-receiver-id-iana-sdp-attribute" toc="include" numbere <section anchor="sec-receiver-id-iana-sdp-attribute">
d="true" removeInRFC="false" pn="section-16.3"> <name>SDP Attribute</name>
<name slugifiedName="name-new-sdp-attribute">New SDP Attribute</name> <t>
<t indent="0" pn="section-16.3-1">
This document updates the SDP media-level attribute, This document updates the SDP media-level attribute,
'bundle-only', according to the following data: 'bundle-only', in the "attribute-name (formerly 'att-field')" subregistr y of the "Session Description Protocol (SDP) Parameters" registry according to t he following data:
</t> </t>
<ul empty="true" bare="false" indent="3" spacing="normal" pn="section-16 <dl spacing="compact">
.3-2"> <dt>Attribute name:</dt>
<li pn="section-16.3-2.1"> <dd>bundle-only</dd>
<dl newline="false" spacing="normal" indent="3" pn="section-16.3-2.1 <dt>Type of attribute:</dt>
.1"> <dd>media</dd>
<dt pn="section-16.3-2.1.1.1">Attribute name:</dt> <dt>Subject to charset:</dt>
<dd pn="section-16.3-2.1.1.2">bundle-only</dd> <dd>No</dd>
<dt pn="section-16.3-2.1.1.3">Type of attribute:</dt> <dt>Purpose:</dt>
<dd pn="section-16.3-2.1.1.4">media</dd> <dd>Request a media description to be accepted
<dt pn="section-16.3-2.1.1.5">Subject to charset:</dt>
<dd pn="section-16.3-2.1.1.6">No</dd>
<dt pn="section-16.3-2.1.1.7">Purpose:</dt>
<dd pn="section-16.3-2.1.1.8">Request a media description to be ac
cepted
in the answer only if kept within a BUNDLE in the answer only if kept within a BUNDLE
group by the answerer.</dd> group by the answerer.</dd>
<dt pn="section-16.3-2.1.1.9">Appropriate values:</dt> <dt>Appropriate values:</dt>
<dd pn="section-16.3-2.1.1.10">N/A</dd> <dd>N/A</dd>
<dt pn="section-16.3-2.1.1.11">Contact name:</dt> <dt>Contact name:</dt>
<dd pn="section-16.3-2.1.1.12">IESG</dd> <dd>IESG</dd>
<dt pn="section-16.3-2.1.1.13">Contact e-mail:</dt> <dt>Contact e-mail:</dt>
<dd pn="section-16.3-2.1.1.14">iesg@ietf.org</dd> <dd>iesg@ietf.org</dd>
<dt pn="section-16.3-2.1.1.15">Reference:</dt> <dt>Reference:</dt>
<dd pn="section-16.3-2.1.1.16">RFC XXXX</dd> <dd>RFC 9143</dd>
<dt pn="section-16.3-2.1.1.17">Mux category:</dt> <dt>Mux category:</dt>
<dd pn="section-16.3-2.1.1.18">NORMAL</dd> <dd>NORMAL</dd>
</dl> </dl>
</li>
</ul>
</section> </section>
<section anchor="sec-receiver-id-iana-sdp-group-semantics" toc="include" n <section anchor="sec-receiver-id-iana-sdp-group-semantics">
umbered="true" removeInRFC="false" pn="section-16.4"> <name>SDP Group Semantics</name>
<name slugifiedName="name-new-sdp-group-semantics">New SDP Group Semanti <t>
cs</name>
<t indent="0" pn="section-16.4-1">
This document updates the following semantics in the This document updates the following semantics in the
"Semantics for the 'group' SDP Attribute" subregistry (under the "Semantics for the 'group' SDP Attribute" subregistry (under the
"Session Description Protocol (SDP) Parameters" registry): "Session Description Protocol (SDP) Parameters" registry):
</t> </t>
<table anchor="Table_1" align="left" pn="table-1"> <table anchor="Table_1" align="left">
<name>Update to SDP Group Semantics</name>
<thead> <thead>
<tr> <tr>
<th align="left" colspan="1" rowspan="1">Semantics</th> <th>Semantics</th>
<th align="left" colspan="1" rowspan="1">Token</th> <th>Token</th>
<th align="left" colspan="1" rowspan="1">Mux Category</th> <th>Mux Category</th>
<th align="left" colspan="1" rowspan="1">Reference</th> <th>Reference</th>
</tr> </tr>
</thead> </thead>
<tbody> <tbody>
<tr> <tr>
<td align="left" colspan="1" rowspan="1">Media bundling</td> <td>Media bundling</td>
<td align="left" colspan="1" rowspan="1">BUNDLE</td> <td>BUNDLE</td>
<td align="left" colspan="1" rowspan="1">NORMAL</td> <td>NORMAL</td>
<td align="left" colspan="1" rowspan="1">RFC XXXX</td> <td>RFC 9143</td>
</tr> </tr>
</tbody> </tbody>
</table> </table>
</section> </section>
</section> </section>
<section anchor="sec-security" toc="include" numbered="true" removeInRFC="fa <section anchor="sec-security">
lse" pn="section-17"> <name>Security Considerations</name>
<name slugifiedName="name-security-considerations">Security Considerations <t>The security considerations defined in <xref target="RFC3264"/> and <xr
</name> ef target="RFC5888"/> apply to the BUNDLE extension. BUNDLE
<t indent="0" pn="section-17-1">The security considerations defined in <xr
ef format="default" target="RFC3264" sectionFormat="of" derivedContent="RFC3264"
/> and <xref format="default" target="RFC5888" sectionFormat="of" derivedContent
="RFC5888"/> apply to the BUNDLE extension. BUNDLE
does not change which information, e.g., RTP streams, flows over does not change which information, e.g., RTP streams, flows over
the network, except for the usage of the MID SDES item as the network, except for the usage of the MID SDES item as
discussed below. discussed below.
Primarily, it changes which addresses and ports, and Primarily, it changes which addresses and ports, and
thus in which (RTP) sessions, the information flows to. This thus in which (RTP) sessions, the information flows to. This
affects the security contexts being used and can cause previously affects the security contexts being used and can cause previously
separated information flows to share the same security context. This has v ery separated information flows to share the same security context. This has v ery
little impact on the performance of the security mechanism of the RTP little impact on the performance of the security mechanism of the RTP
sessions. In cases where one would have applied different security sessions. In cases where one would have applied different security
policies on the different RTP streams being bundled, or where the policies on the different RTP streams being bundled or where the
parties having access to the security contexts would have differed parties having access to the security contexts would have differed
between the RTP streams, additional analysis of the implications are between the RTP streams, additional analysis of the implications is
needed before selecting to apply BUNDLE.</t> needed before selecting to apply BUNDLE.</t>
<t indent="0" pn="section-17-2">The identification-tag, independent of tra
nsport, RTCP SDES packet, or <t>The identification-tag, independent of transport, RTCP SDES packet, or
RTP header extension, can expose the value to parties beyond the RTP header extension, can expose the value to parties beyond the
signaling chain. Therefore, the identification-tag values <bcp14>MUST</bcp 14> be signaling chain. Therefore, the identification-tag values <bcp14>MUST</bcp 14> be
generated in a fashion that does not leak user information, e.g., generated in a fashion that does not leak user information, e.g.,
randomly or using a per-bundle group counter, and <bcp14>SHOULD</bcp14> be 3 bytes or randomly or using a per-bundle group counter, and <bcp14>SHOULD</bcp14> be 3 bytes or
fewer to allow them to efficiently fit into the MID RTP header fewer to allow them to efficiently fit into the MID RTP header
extension. Note that if implementations use different methods for extension. Note that if implementations use different methods for
generating identification-tags, this could enable fingerprinting of the generating identification-tags, this could enable fingerprinting of the
implementation making it vulnerable to targeted attacks. The implementation, making it vulnerable to targeted attacks. The
identification-tag is exposed on the RTP stream level when included in identification-tag is exposed on the RTP stream level when included in
the RTP header extensions; however, what it reveals of the RTP media the RTP header extensions; however, what it reveals of the RTP media
stream structure of the endpoint and application was already possible to stream structure of the endpoint and application was already possible to
deduce from the RTP streams without the MID SDES header extensions. As deduce from the RTP streams without the MID SDES header extensions. As
the identification-tag is also used to route the media stream to the the identification-tag is also used to route the media stream to the
right application functionality, it is important that the value right application functionality, it is important that the value
received is the one intended by the sender; thus, integrity and the received is the one intended by the sender; thus, integrity and the
authenticity of the source are important to prevent denial of service on authenticity of the source are important to prevent denial of service on
the application. Existing SRTP configurations and other security the application. Existing SRTP configurations and other security
mechanisms protecting the whole RTP/RTCP packets will provide the mechanisms protecting the whole RTP/RTCP packets will provide the
necessary protection.</t> necessary protection.</t>
<t indent="0" pn="section-17-3">When the BUNDLE extension is used, the set of configurations of the <t>When the BUNDLE extension is used, the set of configurations of the
security mechanism used in all the bundled media descriptions will need to security mechanism used in all the bundled media descriptions will need to
be compatible so that they can be used simultaneously, at least be compatible so that they can be used simultaneously, at least
per direction or endpoint. When using SRTP, this will be the case, at l east per direction or endpoint. When using SRTP, this will be the case, at l east
for the IETF-defined key-management solutions due to their SDP attribut es for the IETF-defined key-management solutions due to their SDP attribut es
("a=crypto", "a=fingerprint", "a=mikey") and their classification in <x ("a=crypto", "a=fingerprint", "a=mikey") and their classification in <x
ref target="RFC8859" format="default" sectionFormat="of" derivedContent="RFC8859 ref target="RFC8859"/>.</t>
"/>.</t> <t>The security considerations of "RTP Header
<t indent="0" pn="section-17-4">The security considerations of "RTP Header
Extension for the RTP Control Protocol (RTCP) Source Description Items" Extension for the RTP Control Protocol (RTCP) Source Description Items"
<xref target="RFC7941" format="default" sectionFormat="of" derivedConte nt="RFC7941"/> require that when RTCP is confidentiality protected, any SDES <xref target="RFC7941"/> require that when RTCP is confidentiality prot ected, any SDES
RTP header extension carrying an SDES item, such as the MID RTP header RTP header extension carrying an SDES item, such as the MID RTP header
extension, is also protected using commensurate strength algorithms. extension, is also protected using commensurate strength algorithms.
However, assuming the above requirements and recommendations are However, assuming the above requirements and recommendations are
followed, there are no known significant security risks with leaving the followed, there are no known significant security risks with leaving the
MID RTP header extension without confidentiality protection. MID RTP header extension without confidentiality protection.
Therefore, this specification updates RFC 7941 by adding the exception tha t this requirement Therefore, this specification updates <xref target="RFC7941"/> by adding t he exception that this requirement
<bcp14>MAY</bcp14> be ignored for the MID RTP header extension. Security m echanisms for RTP/RTCP are <bcp14>MAY</bcp14> be ignored for the MID RTP header extension. Security m echanisms for RTP/RTCP are
discussed in "Options for Securing RTP Sessions" <xref target="RFC7201" fo discussed in "Options for Securing RTP Sessions" <xref target="RFC7201"/>;
rmat="default" sectionFormat="of" derivedContent="RFC7201"/>, for example, SRTP <xref target="RFC3711"/> can provide the necessary secur
for example, SRTP <xref target="RFC3711" format="default" sectionFormat="o ity
f" derivedContent="RFC3711"/> can provide the necessary security
functions of ensuring the integrity and source authenticity. functions of ensuring the integrity and source authenticity.
</t> </t>
</section> </section>
<section anchor="sec-example-alt1" toc="include" numbered="true" removeInRFC <section anchor="sec-example-alt1">
="false" pn="section-18"> <name>Examples</name>
<name slugifiedName="name-examples">Examples</name> <section anchor="sec-example-add">
<section anchor="sec-example-add" toc="include" numbered="true" removeInRF <name>Example: Tagged "m=" Section Selections</name>
C="false" pn="section-18.1"> <t>
<name slugifiedName="name-example-tagged-m-section-se">Example: Tagged "
m=" Section Selections</name>
<t indent="0" pn="section-18.1-1">
The example below shows: The example below shows:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
8.1-2"> <li>An initial BUNDLE offer, in which the offerer wants to
<li pn="section-18.1-2.1">An initial BUNDLE offer, in which the offere
r wants to
negotiate a BUNDLE group and indicates the audio "m=" negotiate a BUNDLE group and indicates the audio "m="
section as the suggested offerer-tagged "m=" section.</li> section as the suggested offerer-tagged "m=" section.</li>
<li pn="section-18.1-2.2">An initial BUNDLE answer, in which the answe rer accepts <li>An initial BUNDLE answer, in which the answerer accepts
the creation of the BUNDLE group, selects the audio "m=" the creation of the BUNDLE group, selects the audio "m="
section in the offer as the offerer-tagged "m=" section, section in the offer as the offerer-tagged "m=" section,
selects the audio "m=" section in the answer as the selects the audio "m=" section in the answer as the
answerer-tagged "m=" section, and assigns the answerer BUNDLE answerer-tagged "m=" section, and assigns the answerer BUNDLE
address:port to that "m=" section.</li> address:port to that "m=" section.</li>
</ul> </ul>
<t keepWithNext="true" indent="0" pn="section-18.1-3">SDP Offer (1)</t> <t keepWithNext="true">SDP Offer (1)</t>
<sourcecode type="sdp" markers="false" pn="section-18.1-4"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2636 skipping to change at line 2303
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 10002 RTP/AVP 31 32 m=video 10002 RTP/AVP 31 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtcp-mux a=rtcp-mux
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-18.1-5">SDP Answer (2)</t> <t keepWithNext="true">SDP Answer (2)</t>
<sourcecode type="sdp" markers="false" pn="section-18.1-6"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2659 skipping to change at line 2326
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 20000 RTP/AVP 32 m=video 20000 RTP/AVP 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
<section anchor="sec-example-bunrej" toc="include" numbered="true" removeI <section anchor="sec-example-bunrej">
nRFC="false" pn="section-18.2"> <name>Example: BUNDLE Group Rejected</name>
<name slugifiedName="name-example-bundle-group-reject">Example: BUNDLE G <t>
roup Rejected</name>
<t indent="0" pn="section-18.2-1">
The example below shows: The example below shows:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
8.2-2"> <li>An initial BUNDLE offer, in which the offerer wants to
<li pn="section-18.2-2.1">An initial BUNDLE offer, in which the offere
r wants to
negotiate a BUNDLE group and indicates the audio "m=" section negotiate a BUNDLE group and indicates the audio "m=" section
as the suggested offerer-tagged "m=" section.</li> as the suggested offerer-tagged "m=" section.</li>
<li pn="section-18.2-2.2">An initial BUNDLE answer, in which the answe rer rejects <li>An initial BUNDLE answer, in which the answerer rejects
the creation of the BUNDLE group, generates a normal answer, the creation of the BUNDLE group, generates a normal answer,
and assigns a unique address:port to each "m=" section in and assigns a unique address:port to each "m=" section in
the answer.</li> the answer.</li>
</ul> </ul>
<t keepWithNext="true" indent="0" pn="section-18.2-3">SDP Offer (1)</t> <t keepWithNext="true">SDP Offer (1)</t>
<sourcecode type="sdp" markers="false" pn="section-18.2-4"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2699 skipping to change at line 2366
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 10002 RTP/AVP 31 32 m=video 10002 RTP/AVP 31 32
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtcp-mux a=rtcp-mux
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-18.2-5">SDP Answer (2)</t> <t keepWithNext="true">SDP Answer (2)</t>
<sourcecode type="sdp" markers="false" pn="section-18.2-6"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=rtcp-mux a=rtcp-mux
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
m=video 30000 RTP/AVP 32 m=video 30000 RTP/AVP 32
b=AS:1000 b=AS:1000
a=rtcp-mux a=rtcp-mux
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
</sourcecode> </sourcecode>
</section> </section>
<section anchor="sec-example-off-add" toc="include" numbered="true" remove <section anchor="sec-example-off-add">
InRFC="false" pn="section-18.3"> <name>Example: Offerer Adds a Media Description to a BUNDLE Group</name>
<name slugifiedName="name-example-offerer-adds-a-medi">Example: Offerer <t>
Adds a Media Description to a BUNDLE Group</name>
<t indent="0" pn="section-18.3-1">
The example below shows: The example below shows:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
8.3-2"> <li>A subsequent offer, in which the offerer adds a new bundled "m=" s
<li pn="section-18.3-2.1">A subsequent offer, in which the offerer add ection (video), indicated by the "zen"
s a new bundled "m=" section (video), indicated by the "zen"
identification-tag, to a previously negotiated BUNDLE group; indicates the new "m=" section as the identification-tag, to a previously negotiated BUNDLE group; indicates the new "m=" section as the
offerer-tagged "m=" section; and assigns the offerer BUNDLE address:po rt to that "m=" section.</li> offerer-tagged "m=" section; and assigns the offerer BUNDLE address:po rt to that "m=" section.</li>
<li pn="section-18.3-2.2">A subsequent answer, in which the answerer i ndicates the new video "m=" section in the answer as the answerer-tagged "m=" se ction <li>A subsequent answer, in which the answerer indicates the new video "m=" section in the answer as the answerer-tagged "m=" section
and assigns the answerer BUNDLE address:port to that "m=" section.</li > and assigns the answerer BUNDLE address:port to that "m=" section.</li >
</ul> </ul>
<t keepWithNext="true" indent="0" pn="section-18.3-3">SDP Offer (1)</t> <t keepWithNext="true">SDP Offer (1)</t>
<sourcecode type="sdp" markers="false" pn="section-18.3-4"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE zen foo bar a=group:BUNDLE zen foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2761 skipping to change at line 2428
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 10000 RTP/AVP 66 m=video 10000 RTP/AVP 66
b=AS:1000 b=AS:1000
a=mid:zen a=mid:zen
a=rtcp-mux a=rtcp-mux
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-18.3-5">SDP Answer (2)</t> <t keepWithNext="true">SDP Answer (2)</t>
<sourcecode type="sdp" markers="false" pn="section-18.3-6"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
a=group:BUNDLE zen foo bar a=group:BUNDLE zen foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2790 skipping to change at line 2457
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 20000 RTP/AVP 66 m=video 20000 RTP/AVP 66
b=AS:1000 b=AS:1000
a=mid:zen a=mid:zen
a=rtcp-mux a=rtcp-mux
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
</sourcecode> </sourcecode>
</section> </section>
<section anchor="sec-example-off-mov" toc="include" numbered="true" remove <section anchor="sec-example-off-mov">
InRFC="false" pn="section-18.4"> <name>Example: Offerer Moves a Media Description Out of a BUNDLE Group</
<name slugifiedName="name-example-offerer-moves-a-med">Example: Offerer name>
Moves a Media Description Out of a BUNDLE Group</name> <t>
<t indent="0" pn="section-18.4-1">
The example below shows: The example below shows:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
8.4-2"> <li>A subsequent offer, in which the offerer removes an "m=" section (
<li pn="section-18.4-2.1">A subsequent offer, in which the offerer rem video), indicated by the "zen"
oves an "m=" section (video), indicated by the "zen"
identification-tag, from a previously negotiated BUNDLE group; indicat es one of the bundled "m=" sections (audio) identification-tag, from a previously negotiated BUNDLE group; indicat es one of the bundled "m=" sections (audio)
remaining in the BUNDLE group as the offerer-tagged "m=" section; and assigns the offerer BUNDLE address:port to that "m=" section.</li> remaining in the BUNDLE group as the offerer-tagged "m=" section; and assigns the offerer BUNDLE address:port to that "m=" section.</li>
<li pn="section-18.4-2.2">A subsequent answer, in which the answerer r emoves the "m=" section from the BUNDLE group, indicates the audio "m=" section <li>A subsequent answer, in which the answerer removes the "m=" sectio n from the BUNDLE group, indicates the audio "m=" section
in the answer as the answerer-tagged "m=" section, and assigns the ans werer BUNDLE address:port to that "m=" section.</li> in the answer as the answerer-tagged "m=" section, and assigns the ans werer BUNDLE address:port to that "m=" section.</li>
</ul> </ul>
<t keepWithNext="true" indent="0" pn="section-18.4-3">SDP Offer (1)</t> <t keepWithNext="true">SDP Offer (1)</t>
<sourcecode type="sdp" markers="false" pn="section-18.4-4"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2833 skipping to change at line 2500
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 50000 RTP/AVP 66 m=video 50000 RTP/AVP 66
b=AS:1000 b=AS:1000
a=mid:zen a=mid:zen
a=rtcp-mux a=rtcp-mux
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-18.4-5">SDP Answer (2)</t> <t keepWithNext="true">SDP Answer (2)</t>
<sourcecode type="sdp" markers="false" pn="section-18.4-6"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2862 skipping to change at line 2529
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 60000 RTP/AVP 66 m=video 60000 RTP/AVP 66
b=AS:1000 b=AS:1000
a=mid:zen a=mid:zen
a=rtcp-mux a=rtcp-mux
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
</sourcecode> </sourcecode>
</section> </section>
<section anchor="sec-example-off-dis" toc="include" numbered="true" remove <section anchor="sec-example-off-dis">
InRFC="false" pn="section-18.5"> <name>Example: Offerer Disables a Media Description within a BUNDLE Grou
<name slugifiedName="name-example-offerer-disables-a-">Example: Offerer p</name>
Disables a Media Description within a BUNDLE Group</name> <t>
<t indent="0" pn="section-18.5-1">
The example below shows: The example below shows:
</t> </t>
<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-1 <ul>
8.5-2"> <li>A subsequent offer, in which the offerer disables (by assigning a
<li pn="section-18.5-2.1">A subsequent offer, in which the offerer dis zero port value) an "m=" section (video), indicated by the "zen"
ables (by assigning a zero port value) an "m=" section (video), indicated by the
"zen"
identification-tag, from a previously negotiated BUNDLE group; indicat es one of the bundled "m=" sections (audio) identification-tag, from a previously negotiated BUNDLE group; indicat es one of the bundled "m=" sections (audio)
remaining active in the BUNDLE group as the offerer-tagged "m=" sectio n; and assigns the offerer BUNDLE address:port to that "m=" section.</li> remaining active in the BUNDLE group as the offerer-tagged "m=" sectio n; and assigns the offerer BUNDLE address:port to that "m=" section.</li>
<li pn="section-18.5-2.2">A subsequent answer, in which the answerer d isables the "m=" section, indicates the audio "m=" section <li>A subsequent answer, in which the answerer disables the "m=" secti on, indicates the audio "m=" section
in the answer as the answerer-tagged "m=" section, and assigns the ans werer BUNDLE address:port to that "m=" section.</li> in the answer as the answerer-tagged "m=" section, and assigns the ans werer BUNDLE address:port to that "m=" section.</li>
</ul> </ul>
<t keepWithNext="true" indent="0" pn="section-18.5-3">SDP Offer (1)</t> <t keepWithNext="true">SDP Offer (1)</t>
<sourcecode type="sdp" markers="false" pn="section-18.5-4"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP6 2001:db8::3 o=alice 2890844526 2890844526 IN IP6 2001:db8::3
s= s=
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97 m=audio 10000 RTP/AVP 0 8 97
c=IN IP6 2001:db8::3 c=IN IP6 2001:db8::3
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2904 skipping to change at line 2571
b=AS:1000 b=AS:1000
a=mid:bar a=mid:bar
a=rtpmap:31 H261/90000 a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000 a=rtpmap:32 MPV/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
m=video 0 RTP/AVP 66 m=video 0 RTP/AVP 66
a=mid:zen a=mid:zen
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-18.5-5">SDP Answer (2)</t> <t keepWithNext="true">SDP Answer (2)</t>
<sourcecode type="sdp" markers="false" pn="section-18.5-6"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP6 2001:db8::1 o=bob 2808844564 2808844564 IN IP6 2001:db8::1
s= s=
t=0 0 t=0 0
a=group:BUNDLE foo bar a=group:BUNDLE foo bar
m=audio 20000 RTP/AVP 0 m=audio 20000 RTP/AVP 0
c=IN IP6 2001:db8::1 c=IN IP6 2001:db8::1
b=AS:200 b=AS:200
a=mid:foo a=mid:foo
skipping to change at line 2936 skipping to change at line 2603
m=video 0 RTP/AVP 66 m=video 0 RTP/AVP 66
a=mid:zen a=mid:zen
a=rtpmap:66 H261/90000 a=rtpmap:66 H261/90000
</sourcecode> </sourcecode>
</section> </section>
</section> </section>
</middle> </middle>
<back> <back>
<displayreference target="I-D.ietf-avtext-lrr" to="LLR-RTCP"/> <displayreference target="I-D.ietf-avtext-lrr" to="LLR-RTCP"/>
<references pn="section-19"> <references>
<name slugifiedName="name-references">References</name> <name>References</name>
<references pn="section-19.1"> <references>
<name slugifiedName="name-normative-references">Normative References</na <name>Normative References</name>
me>
<reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2 <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.
119" quoteTitle="true" derivedAnchor="RFC2119"> xml"/>
<front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3264.
<title>Key words for use in RFCs to Indicate Requirement Levels</tit xml"/>
le> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3550.
<author initials="S." surname="Bradner" fullname="S. Bradner"> xml"/>
<organization showOnFrontPage="true"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3605.
</author> xml"/>
<date year="1997" month="March"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3629.
<abstract> xml"/>
<t indent="0">In many standards track documents several words are <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3711.
used to signify the requirements in the specification. These words are often ca xml"/>
pitalized. This document defines these words as they should be interpreted in IE <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4566.
TF documents. This document specifies an Internet Best Current Practices for th xml"/>
e Internet Community, and requests discussion and suggestions for improvements.< <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4961.
/t> xml"/>
</abstract> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5761.
</front> xml"/>
<seriesInfo name="BCP" value="14"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5764.
<seriesInfo name="RFC" value="2119"/> xml"/>
<seriesInfo name="DOI" value="10.17487/RFC2119"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5888.
</reference> xml"/>
<reference anchor="RFC3264" target="https://www.rfc-editor.org/info/rfc3 <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6347.
264" quoteTitle="true" derivedAnchor="RFC3264"> xml"/>
<front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7941.
<title>An Offer/Answer Model with Session Description Protocol (SDP) xml"/>
</title> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.
<author initials="J." surname="Rosenberg" fullname="J. Rosenberg"> xml"/>
<organization showOnFrontPage="true"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8285.
</author> xml"/>
<author initials="H." surname="Schulzrinne" fullname="H. Schulzrinne <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8445.
"> xml"/>
<organization showOnFrontPage="true"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8839.
</author> xml"/>
<date year="2002" month="June"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8840.
<abstract> xml"/>
<t indent="0">This document defines a mechanism by which two entit <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8858.
ies can make use of the Session Description Protocol (SDP) to arrive at a common xml"/>
view of a multimedia session between them. In the model, one participant offer <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8859.
s the other a description of the desired session from their perspective, and the xml"/>
other participant answers with the desired session from their perspective. Thi
s offer/answer model is most useful in unicast sessions where information from b
oth participants is needed for the complete view of the session. The offer/answ
er model is used by protocols like the Session Initiation Protocol (SIP). [STAN
DARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3264"/>
<seriesInfo name="DOI" value="10.17487/RFC3264"/>
</reference>
<reference anchor="RFC3550" target="https://www.rfc-editor.org/info/rfc3
550" quoteTitle="true" derivedAnchor="RFC3550">
<front>
<title>RTP: A Transport Protocol for Real-Time Applications</title>
<author initials="H." surname="Schulzrinne" fullname="H. Schulzrinne
">
<organization showOnFrontPage="true"/>
</author>
<author initials="S." surname="Casner" fullname="S. Casner">
<organization showOnFrontPage="true"/>
</author>
<author initials="R." surname="Frederick" fullname="R. Frederick">
<organization showOnFrontPage="true"/>
</author>
<author initials="V." surname="Jacobson" fullname="V. Jacobson">
<organization showOnFrontPage="true"/>
</author>
<date year="2003" month="July"/>
<abstract>
<t indent="0">This memorandum describes RTP, the real-time transpo
rt protocol. RTP provides end-to-end network transport functions suitable for a
pplications transmitting real-time data, such as audio, video or simulation data
, over multicast or unicast network services. RTP does not address resource res
ervation and does not guarantee quality-of- service for real-time services. The
data transport is augmented by a control protocol (RTCP) to allow monitoring of
the data delivery in a manner scalable to large multicast networks, and to prov
ide minimal control and identification functionality. RTP and RTCP are designed
to be independent of the underlying transport and network layers. The protocol
supports the use of RTP-level translators and mixers. Most of the text in this
memorandum is identical to RFC 1889 which it obsoletes. There are no changes in
the packet formats on the wire, only changes to the rules and algorithms govern
ing how the protocol is used. The biggest change is an enhancement to the scalab
le timer algorithm for calculating when to send RTCP packets in order to minimiz
e transmission in excess of the intended rate when many participants join a sess
ion simultaneously. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="STD" value="64"/>
<seriesInfo name="RFC" value="3550"/>
<seriesInfo name="DOI" value="10.17487/RFC3550"/>
</reference>
<reference anchor="RFC3605" target="https://www.rfc-editor.org/info/rfc3
605" quoteTitle="true" derivedAnchor="RFC3605">
<front>
<title>Real Time Control Protocol (RTCP) attribute in Session Descri
ption Protocol (SDP)</title>
<author initials="C." surname="Huitema" fullname="C. Huitema">
<organization showOnFrontPage="true"/>
</author>
<date year="2003" month="October"/>
<abstract>
<t indent="0">The Session Description Protocol (SDP) is used to de
scribe the parameters of media streams used in multimedia sessions. When a sess
ion requires multiple ports, SDP assumes that these ports have consecutive numbe
rs. However, when the session crosses a network address translation device that
also uses port mapping, the ordering of ports can be destroyed by the translati
on. To handle this, we propose an extension attribute to SDP.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3605"/>
<seriesInfo name="DOI" value="10.17487/RFC3605"/>
</reference>
<reference anchor="RFC3629" target="https://www.rfc-editor.org/info/rfc3
629" quoteTitle="true" derivedAnchor="RFC3629">
<front>
<title>UTF-8, a transformation format of ISO 10646</title>
<author initials="F." surname="Yergeau" fullname="F. Yergeau">
<organization showOnFrontPage="true"/>
</author>
<date year="2003" month="November"/>
<abstract>
<t indent="0">ISO/IEC 10646-1 defines a large character set called
the Universal Character Set (UCS) which encompasses most of the world's writing
systems. The originally proposed encodings of the UCS, however, were not compa
tible with many current applications and protocols, and this has led to the deve
lopment of UTF-8, the object of this memo. UTF-8 has the characteristic of pres
erving the full US-ASCII range, providing compatibility with file systems, parse
rs and other software that rely on US-ASCII values but are transparent to other
values. This memo obsoletes and replaces RFC 2279.</t>
</abstract>
</front>
<seriesInfo name="STD" value="63"/>
<seriesInfo name="RFC" value="3629"/>
<seriesInfo name="DOI" value="10.17487/RFC3629"/>
</reference>
<reference anchor="RFC3711" target="https://www.rfc-editor.org/info/rfc3
711" quoteTitle="true" derivedAnchor="RFC3711">
<front>
<title>The Secure Real-time Transport Protocol (SRTP)</title>
<author initials="M." surname="Baugher" fullname="M. Baugher">
<organization showOnFrontPage="true"/>
</author>
<author initials="D." surname="McGrew" fullname="D. McGrew">
<organization showOnFrontPage="true"/>
</author>
<author initials="M." surname="Naslund" fullname="M. Naslund">
<organization showOnFrontPage="true"/>
</author>
<author initials="E." surname="Carrara" fullname="E. Carrara">
<organization showOnFrontPage="true"/>
</author>
<author initials="K." surname="Norrman" fullname="K. Norrman">
<organization showOnFrontPage="true"/>
</author>
<date year="2004" month="March"/>
<abstract>
<t indent="0">This document describes the Secure Real-time Transpo
rt Protocol (SRTP), a profile of the Real-time Transport Protocol (RTP), which c
an provide confidentiality, message authentication, and replay protection to the
RTP traffic and to the control traffic for RTP, the Real-time Transport Control
Protocol (RTCP). [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3711"/>
<seriesInfo name="DOI" value="10.17487/RFC3711"/>
</reference>
<reference anchor="RFC4566" target="https://www.rfc-editor.org/info/rfc4
566" quoteTitle="true" derivedAnchor="RFC4566">
<front>
<title>SDP: Session Description Protocol</title>
<author initials="M." surname="Handley" fullname="M. Handley">
<organization showOnFrontPage="true"/>
</author>
<author initials="V." surname="Jacobson" fullname="V. Jacobson">
<organization showOnFrontPage="true"/>
</author>
<author initials="C." surname="Perkins" fullname="C. Perkins">
<organization showOnFrontPage="true"/>
</author>
<date year="2006" month="July"/>
<abstract>
<t indent="0">This memo defines the Session Description Protocol (
SDP). SDP is intended for describing multimedia sessions for the purposes of se
ssion announcement, session invitation, and other forms of multimedia session in
itiation. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="4566"/>
<seriesInfo name="DOI" value="10.17487/RFC4566"/>
</reference>
<reference anchor="RFC4961" target="https://www.rfc-editor.org/info/rfc4
961" quoteTitle="true" derivedAnchor="RFC4961">
<front>
<title>Symmetric RTP / RTP Control Protocol (RTCP)</title>
<author initials="D." surname="Wing" fullname="D. Wing">
<organization showOnFrontPage="true"/>
</author>
<date year="2007" month="July"/>
<abstract>
<t indent="0">This document recommends using one UDP port pair for
both communication directions of bidirectional RTP and RTP Control Protocol (RT
CP) sessions, commonly called "symmetric RTP" and "symmetric RTCP". This docume
nt specifies an Internet Best Current Practices for the Internet Community, and
requests discussion and suggestions for improvements.</t>
</abstract>
</front>
<seriesInfo name="BCP" value="131"/>
<seriesInfo name="RFC" value="4961"/>
<seriesInfo name="DOI" value="10.17487/RFC4961"/>
</reference>
<reference anchor="RFC5761" target="https://www.rfc-editor.org/info/rfc5
761" quoteTitle="true" derivedAnchor="RFC5761">
<front>
<title>Multiplexing RTP Data and Control Packets on a Single Port</t
itle>
<author initials="C." surname="Perkins" fullname="C. Perkins">
<organization showOnFrontPage="true"/>
</author>
<author initials="M." surname="Westerlund" fullname="M. Westerlund">
<organization showOnFrontPage="true"/>
</author>
<date year="2010" month="April"/>
<abstract>
<t indent="0">This memo discusses issues that arise when multiplex
ing RTP data packets and RTP Control Protocol (RTCP) packets on a single UDP por
t. It updates RFC 3550 and RFC 3551 to describe when such multiplexing is and is
not appropriate, and it explains how the Session Description Protocol (SDP) can
be used to signal multiplexed sessions. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5761"/>
<seriesInfo name="DOI" value="10.17487/RFC5761"/>
</reference>
<reference anchor="RFC5764" target="https://www.rfc-editor.org/info/rfc5
764" quoteTitle="true" derivedAnchor="RFC5764">
<front>
<title>Datagram Transport Layer Security (DTLS) Extension to Establi
sh Keys for the Secure Real-time Transport Protocol (SRTP)</title>
<author initials="D." surname="McGrew" fullname="D. McGrew">
<organization showOnFrontPage="true"/>
</author>
<author initials="E." surname="Rescorla" fullname="E. Rescorla">
<organization showOnFrontPage="true"/>
</author>
<date year="2010" month="May"/>
<abstract>
<t indent="0">This document describes a Datagram Transport Layer S
ecurity (DTLS) extension to establish keys for Secure RTP (SRTP) and Secure RTP
Control Protocol (SRTCP) flows. DTLS keying happens on the media path, independ
ent of any out-of-band signalling channel present. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5764"/>
<seriesInfo name="DOI" value="10.17487/RFC5764"/>
</reference>
<reference anchor="RFC5888" target="https://www.rfc-editor.org/info/rfc5
888" quoteTitle="true" derivedAnchor="RFC5888">
<front>
<title>The Session Description Protocol (SDP) Grouping Framework</ti
tle>
<author initials="G." surname="Camarillo" fullname="G. Camarillo">
<organization showOnFrontPage="true"/>
</author>
<author initials="H." surname="Schulzrinne" fullname="H. Schulzrinne
">
<organization showOnFrontPage="true"/>
</author>
<date year="2010" month="June"/>
<abstract>
<t indent="0">In this specification, we define a framework to grou
p "m" lines in the Session Description Protocol (SDP) for different purposes. T
his framework uses the "group" and "mid" SDP attributes, both of which are defin
ed in this specification. Additionally, we specify how to use the framework for
two different purposes: for lip synchronization and for receiving a media flow
consisting of several media streams on different transport addresses. This docu
ment obsoletes RFC 3388. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5888"/>
<seriesInfo name="DOI" value="10.17487/RFC5888"/>
</reference>
<reference anchor="RFC6347" target="https://www.rfc-editor.org/info/rfc6
347" quoteTitle="true" derivedAnchor="RFC6347">
<front>
<title>Datagram Transport Layer Security Version 1.2</title>
<author initials="E." surname="Rescorla" fullname="E. Rescorla">
<organization showOnFrontPage="true"/>
</author>
<author initials="N." surname="Modadugu" fullname="N. Modadugu">
<organization showOnFrontPage="true"/>
</author>
<date year="2012" month="January"/>
<abstract>
<t indent="0">This document specifies version 1.2 of the Datagram
Transport Layer Security (DTLS) protocol. The DTLS protocol provides communicat
ions privacy for datagram protocols. The protocol allows client/server applicat
ions to communicate in a way that is designed to prevent eavesdropping, tamperin
g, or message forgery. The DTLS protocol is based on the Transport Layer Securi
ty (TLS) protocol and provides equivalent security guarantees. Datagram semanti
cs of the underlying transport are preserved by the DTLS protocol. This documen
t updates DTLS 1.0 to work with TLS version 1.2. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="6347"/>
<seriesInfo name="DOI" value="10.17487/RFC6347"/>
</reference>
<reference anchor="RFC7941" target="https://www.rfc-editor.org/info/rfc7
941" quoteTitle="true" derivedAnchor="RFC7941">
<front>
<title>RTP Header Extension for the RTP Control Protocol (RTCP) Sour
ce Description Items</title>
<author initials="M." surname="Westerlund" fullname="M. Westerlund">
<organization showOnFrontPage="true"/>
</author>
<author initials="B." surname="Burman" fullname="B. Burman">
<organization showOnFrontPage="true"/>
</author>
<author initials="R." surname="Even" fullname="R. Even">
<organization showOnFrontPage="true"/>
</author>
<author initials="M." surname="Zanaty" fullname="M. Zanaty">
<organization showOnFrontPage="true"/>
</author>
<date year="2016" month="August"/>
<abstract>
<t indent="0">Source Description (SDES) items are normally transpo
rted in the RTP Control Protocol (RTCP). In some cases, it can be beneficial to
speed up the delivery of these items. The main case is when a new synchronizat
ion source (SSRC) joins an RTP session and the receivers need this source's iden
tity, relation to other sources, or its synchronization context, all of which ma
y be fully or partially identified using SDES items. To enable this optimizatio
n, this document specifies a new RTP header extension that can carry SDES items.
</t>
</abstract>
</front>
<seriesInfo name="RFC" value="7941"/>
<seriesInfo name="DOI" value="10.17487/RFC7941"/>
</reference>
<reference anchor="RFC8174" target="https://www.rfc-editor.org/info/rfc8
174" quoteTitle="true" derivedAnchor="RFC8174">
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</ti
tle>
<author initials="B." surname="Leiba" fullname="B. Leiba">
<organization showOnFrontPage="true"/>
</author>
<date year="2017" month="May"/>
<abstract>
<t indent="0">RFC 2119 specifies common key words that may be used
in protocol specifications. This document aims to reduce the ambiguity by cla
rifying that only UPPERCASE usage of the key words have the defined special mea
nings.</t>
</abstract>
</front>
<seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="8174"/>
<seriesInfo name="DOI" value="10.17487/RFC8174"/>
</reference>
<reference anchor="RFC8285" target="https://www.rfc-editor.org/info/rfc8
285" quoteTitle="true" derivedAnchor="RFC8285">
<front>
<title>A General Mechanism for RTP Header Extensions</title>
<author initials="D." surname="Singer" fullname="D. Singer">
<organization showOnFrontPage="true"/>
</author>
<author initials="H." surname="Desineni" fullname="H. Desineni">
<organization showOnFrontPage="true"/>
</author>
<author initials="R." surname="Even" fullname="R. Even" role="editor
">
<organization showOnFrontPage="true"/>
</author>
<date year="2017" month="October"/>
<abstract>
<t indent="0">This document provides a general mechanism to use th
e header extension feature of RTP (the Real-time Transport Protocol). It provid
es the option to use a small number of small extensions in each RTP packet, wher
e the universe of possible extensions is large and registration is decentralized
. The actual extensions in use in a session are signaled in the setup informati
on for that session. This document obsoletes RFC 5285.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="8285"/>
<seriesInfo name="DOI" value="10.17487/RFC8285"/>
</reference>
<reference anchor="RFC8445" target="https://www.rfc-editor.org/info/rfc8
445" quoteTitle="true" derivedAnchor="RFC8445">
<front>
<title>Interactive Connectivity Establishment (ICE): A Protocol for
Network Address Translator (NAT) Traversal</title>
<author initials="A." surname="Keranen" fullname="A. Keranen">
<organization showOnFrontPage="true"/>
</author>
<author initials="C." surname="Holmberg" fullname="C. Holmberg">
<organization showOnFrontPage="true"/>
</author>
<author initials="J." surname="Rosenberg" fullname="J. Rosenberg">
<organization showOnFrontPage="true"/>
</author>
<date year="2018" month="July"/>
<abstract>
<t indent="0">This document describes a protocol for Network Addre
ss Translator (NAT) traversal for UDP-based communication. This protocol is cal
led Interactive Connectivity Establishment (ICE). ICE makes use of the Session
Traversal Utilities for NAT (STUN) protocol and its extension, Traversal Using R
elay NAT (TURN).</t>
<t indent="0">This document obsoletes RFC 5245.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="8445"/>
<seriesInfo name="DOI" value="10.17487/RFC8445"/>
</reference>
<reference anchor="RFC8839" target="https://www.rfc-editor.org/info/rfc8
839" quoteTitle="true" derivedAnchor="RFC8839">
<front>
<title>Session Description Protocol (SDP) Offer/Answer Procedures fo
r Interactive Connectivity Establishment (ICE)</title>
<author initials="M" surname="Petit-Huguenin" fullname="Marc Petit-H
uguenin">
<organization showOnFrontPage="true"/>
</author>
<author initials="S" surname="Nandakumar" fullname="Suhas Nandakumar
">
<organization showOnFrontPage="true"/>
</author>
<author initials="C" surname="Holmberg" fullname="Christer Holmberg"
>
<organization showOnFrontPage="true"/>
</author>
<author initials="A" surname="Keranen" fullname="Ari Keranen">
<organization showOnFrontPage="true"/>
</author>
<author initials="R" surname="Shpount" fullname="Roman Shpount">
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8839"/>
<seriesInfo name="DOI" value="10.17487/RFC8839"/>
</reference>
<reference anchor="RFC8840" target="https://www.rfc-editor.org/info/rfc8
840" quoteTitle="true" derivedAnchor="RFC8840">
<front>
<title>A Session Initiation Protocol (SIP) Usage for Incremental Pro
visioning of Candidates for the Interactive Connectivity Establishment (Trickle
ICE)</title>
<author initials="E" surname="Ivov" fullname="Emil Ivov">
<organization showOnFrontPage="true"/>
</author>
<author initials="T" surname="Stach" fullname="Thomas Stach">
<organization showOnFrontPage="true"/>
</author>
<author initials="E" surname="Marocco" fullname="Enrico Marocco">
<organization showOnFrontPage="true"/>
</author>
<author initials="C" surname="Holmberg" fullname="Christer Holmberg"
>
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8840"/>
<seriesInfo name="DOI" value="10.17487/RFC8840"/>
</reference>
<reference anchor="RFC8858" target="https://www.rfc-editor.org/info/rfc8
858" quoteTitle="true" derivedAnchor="RFC8858">
<front>
<title>Indicating Exclusive Support of RTP and RTP Control Protocol
(RTCP) Multiplexing Using the Session Description Protocol (SDP)</title>
<author initials="C." surname="Holmberg" fullname="Christer Holmberg
">
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8858"/>
<seriesInfo name="DOI" value="10.17487/RFC8858"/>
</reference>
<reference anchor="RFC8859" target="https://www.rfc-editor.org/info/rfc8
859" quoteTitle="true" derivedAnchor="RFC8859">
<front>
<title>A Framework for Session Description Protocol (SDP) Attributes
When Multiplexing</title>
<author initials="S" surname="Nandakumar" fullname="Suhas Nandakumar
">
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8859"/>
<seriesInfo name="DOI" value="10.17487/RFC8859"/>
</reference>
</references> </references>
<references pn="section-19.2"> <references>
<name slugifiedName="name-informative-references">Informative References <name>Informative References</name>
</name>
<reference anchor="I-D.ietf-avtext-lrr" quoteTitle="true" target="https: <xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D.ietf-av
//datatracker.ietf.org/doc/html/draft-ietf-avtext-lrr-07" derivedAnchor="LLR-RTC text-lrr.xml"/>
P">
<front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2543.
<title>The Layer Refresh Request (LRR) RTCP Feedback Message</title> xml"/>
<author initials="J" surname="Lennox" fullname="Jonathan Lennox"> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3261.
<organization showOnFrontPage="true"/> xml"/>
</author> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3611.
<author initials="D" surname="Hong" fullname="Danny Hong"> xml"/>
<organization showOnFrontPage="true"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4585.
</author> xml"/>
<author initials="J" surname="Uberti" fullname="Justin Uberti"> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5104.
<organization showOnFrontPage="true"/> xml"/>
</author> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5576.
<author initials="S" surname="Holmer" fullname="Stefan Holmer"> xml"/>
<organization showOnFrontPage="true"/> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7160.
</author> xml"/>
<author initials="M" surname="Flodman" fullname="Magnus Flodman"> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7201.
<organization showOnFrontPage="true"/> xml"/>
</author> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7656.
<date month="July" day="2" year="2017"/> xml"/>
<abstract> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7657.
<t indent="0">This memo describes the RTCP Payload-Specific Feedba xml"/>
ck Message "Layer Refresh Request" (LRR), which can be used to request a state r <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8829.
efresh of one or more substreams of a layered media stream. It also defines its xml"/>
use with several RTP payloads for scalable media formats.</t> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8838.
</abstract> xml"/>
</front> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8843.
<seriesInfo name="Internet-Draft" value="draft-ietf-avtext-lrr-07"/> xml"/>
<format type="TXT" target="https://datatracker.ietf.org/doc/html/draft
-ietf-avtext-lrr-07"/> <reference anchor="Err6431" quote-title="false" target="https://www.rfc-editor.o
<refcontent>Work in Progress</refcontent> rg/errata/eid6431">
</reference> <front>
<reference anchor="RFC2543" target="https://www.rfc-editor.org/info/rfc2 <title>Erratum ID 6431</title>
543" quoteTitle="true" derivedAnchor="RFC2543"> <author>
<front> <organization>RFC Errata</organization>
<title>SIP: Session Initiation Protocol</title> </author>
<author initials="M." surname="Handley" fullname="M. Handley"> </front>
<organization showOnFrontPage="true"/> <refcontent>RFC 8843</refcontent>
</author> </reference>
<author initials="H." surname="Schulzrinne" fullname="H. Schulzrinne
"> <reference anchor="Err6437" quote-title="false" target="https://www.rfc-editor.o
<organization showOnFrontPage="true"/> rg/errata/eid6437">
</author> <front>
<author initials="E." surname="Schooler" fullname="E. Schooler"> <title>Erratum ID 6437</title>
<organization showOnFrontPage="true"/> <author>
</author> <organization>RFC Errata</organization>
<author initials="J." surname="Rosenberg" fullname="J. Rosenberg"> </author>
<organization showOnFrontPage="true"/> </front>
</author> <refcontent>RFC 8843</refcontent>
<date year="1999" month="March"/> </reference>
<abstract>
<t indent="0">The Session Initiation Protocol (SIP) is an applicat
ion-layer control (signaling) protocol for creating, modifying and terminating s
essions with one or more participants. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="2543"/>
<seriesInfo name="DOI" value="10.17487/RFC2543"/>
</reference>
<reference anchor="RFC3261" target="https://www.rfc-editor.org/info/rfc3
261" quoteTitle="true" derivedAnchor="RFC3261">
<front>
<title>SIP: Session Initiation Protocol</title>
<author initials="J." surname="Rosenberg" fullname="J. Rosenberg">
<organization showOnFrontPage="true"/>
</author>
<author initials="H." surname="Schulzrinne" fullname="H. Schulzrinne
">
<organization showOnFrontPage="true"/>
</author>
<author initials="G." surname="Camarillo" fullname="G. Camarillo">
<organization showOnFrontPage="true"/>
</author>
<author initials="A." surname="Johnston" fullname="A. Johnston">
<organization showOnFrontPage="true"/>
</author>
<author initials="J." surname="Peterson" fullname="J. Peterson">
<organization showOnFrontPage="true"/>
</author>
<author initials="R." surname="Sparks" fullname="R. Sparks">
<organization showOnFrontPage="true"/>
</author>
<author initials="M." surname="Handley" fullname="M. Handley">
<organization showOnFrontPage="true"/>
</author>
<author initials="E." surname="Schooler" fullname="E. Schooler">
<organization showOnFrontPage="true"/>
</author>
<date year="2002" month="June"/>
<abstract>
<t indent="0">This document describes Session Initiation Protocol
(SIP), an application-layer control (signaling) protocol for creating, modifying
, and terminating sessions with one or more participants. These sessions includ
e Internet telephone calls, multimedia distribution, and multimedia conferences.
[STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3261"/>
<seriesInfo name="DOI" value="10.17487/RFC3261"/>
</reference>
<reference anchor="RFC3611" target="https://www.rfc-editor.org/info/rfc3
611" quoteTitle="true" derivedAnchor="RFC3611">
<front>
<title>RTP Control Protocol Extended Reports (RTCP XR)</title>
<author initials="T." surname="Friedman" fullname="T. Friedman" role
="editor">
<organization showOnFrontPage="true"/>
</author>
<author initials="R." surname="Caceres" fullname="R. Caceres" role="
editor">
<organization showOnFrontPage="true"/>
</author>
<author initials="A." surname="Clark" fullname="A. Clark" role="edit
or">
<organization showOnFrontPage="true"/>
</author>
<date year="2003" month="November"/>
<abstract>
<t indent="0">This document defines the Extended Report (XR) packe
t type for the RTP Control Protocol (RTCP), and defines how the use of XR packet
s can be signaled by an application if it employs the Session Description Protoc
ol (SDP). XR packets are composed of report blocks, and seven block types are d
efined here. The purpose of the extended reporting format is to convey informat
ion that supplements the six statistics that are contained in the report blocks
used by RTCP's Sender Report (SR) and Receiver Report (RR) packets. Some applic
ations, such as multicast inference of network characteristics (MINC) or voice o
ver IP (VoIP) monitoring, require other and more detailed statistics. In additi
on to the block types defined here, additional block types may be defined in the
future by adhering to the framework that this document provides.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3611"/>
<seriesInfo name="DOI" value="10.17487/RFC3611"/>
</reference>
<reference anchor="RFC4585" target="https://www.rfc-editor.org/info/rfc4
585" quoteTitle="true" derivedAnchor="RFC4585">
<front>
<title>Extended RTP Profile for Real-time Transport Control Protocol
(RTCP)-Based Feedback (RTP/AVPF)</title>
<author initials="J." surname="Ott" fullname="J. Ott">
<organization showOnFrontPage="true"/>
</author>
<author initials="S." surname="Wenger" fullname="S. Wenger">
<organization showOnFrontPage="true"/>
</author>
<author initials="N." surname="Sato" fullname="N. Sato">
<organization showOnFrontPage="true"/>
</author>
<author initials="C." surname="Burmeister" fullname="C. Burmeister">
<organization showOnFrontPage="true"/>
</author>
<author initials="J." surname="Rey" fullname="J. Rey">
<organization showOnFrontPage="true"/>
</author>
<date year="2006" month="July"/>
<abstract>
<t indent="0">Real-time media streams that use RTP are, to some de
gree, resilient against packet losses. Receivers may use the base mechanisms of
the Real-time Transport Control Protocol (RTCP) to report packet reception stat
istics and thus allow a sender to adapt its transmission behavior in the mid-ter
m. This is the sole means for feedback and feedback-based error repair (besides
a few codec-specific mechanisms). This document defines an extension to the Au
dio-visual Profile (AVP) that enables receivers to provide, statistically, more
immediate feedback to the senders and thus allows for short-term adaptation and
efficient feedback-based repair mechanisms to be implemented. This early feedba
ck profile (AVPF) maintains the AVP bandwidth constraints for RTCP and preserves
scalability to large groups. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="4585"/>
<seriesInfo name="DOI" value="10.17487/RFC4585"/>
</reference>
<reference anchor="RFC5104" target="https://www.rfc-editor.org/info/rfc5
104" quoteTitle="true" derivedAnchor="RFC5104">
<front>
<title>Codec Control Messages in the RTP Audio-Visual Profile with F
eedback (AVPF)</title>
<author initials="S." surname="Wenger" fullname="S. Wenger">
<organization showOnFrontPage="true"/>
</author>
<author initials="U." surname="Chandra" fullname="U. Chandra">
<organization showOnFrontPage="true"/>
</author>
<author initials="M." surname="Westerlund" fullname="M. Westerlund">
<organization showOnFrontPage="true"/>
</author>
<author initials="B." surname="Burman" fullname="B. Burman">
<organization showOnFrontPage="true"/>
</author>
<date year="2008" month="February"/>
<abstract>
<t indent="0">This document specifies a few extensions to the mess
ages defined in the Audio-Visual Profile with Feedback (AVPF). They are helpful
primarily in conversational multimedia scenarios where centralized multipoint f
unctionalities are in use. However, some are also usable in smaller multicast e
nvironments and point-to-point calls.</t>
<t indent="0">The extensions discussed are messages related to the
ITU-T Rec. H.271 Video Back Channel, Full Intra Request, Temporary Maximum Medi
a Stream Bit Rate, and Temporal-Spatial Trade-off. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5104"/>
<seriesInfo name="DOI" value="10.17487/RFC5104"/>
</reference>
<reference anchor="RFC5576" target="https://www.rfc-editor.org/info/rfc5
576" quoteTitle="true" derivedAnchor="RFC5576">
<front>
<title>Source-Specific Media Attributes in the Session Description P
rotocol (SDP)</title>
<author initials="J." surname="Lennox" fullname="J. Lennox">
<organization showOnFrontPage="true"/>
</author>
<author initials="J." surname="Ott" fullname="J. Ott">
<organization showOnFrontPage="true"/>
</author>
<author initials="T." surname="Schierl" fullname="T. Schierl">
<organization showOnFrontPage="true"/>
</author>
<date year="2009" month="June"/>
<abstract>
<t indent="0">The Session Description Protocol (SDP) provides mech
anisms to describe attributes of multimedia sessions and of individual media str
eams (e.g., Real-time Transport Protocol (RTP) sessions) within a multimedia ses
sion, but does not provide any mechanism to describe individual media sources wi
thin a media stream. This document defines a mechanism to describe RTP media so
urces, which are identified by their synchronization source (SSRC) identifiers,
in SDP, to associate attributes with these sources, and to express relationships
among sources. It also defines several source-level attributes that can be use
d to describe properties of media sources. [STANDARDS-TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5576"/>
<seriesInfo name="DOI" value="10.17487/RFC5576"/>
</reference>
<reference anchor="RFC7160" target="https://www.rfc-editor.org/info/rfc7
160" quoteTitle="true" derivedAnchor="RFC7160">
<front>
<title>Support for Multiple Clock Rates in an RTP Session</title>
<author initials="M." surname="Petit-Huguenin" fullname="M. Petit-Hu
guenin">
<organization showOnFrontPage="true"/>
</author>
<author initials="G." surname="Zorn" fullname="G. Zorn" role="editor
">
<organization showOnFrontPage="true"/>
</author>
<date year="2014" month="April"/>
<abstract>
<t indent="0">This document clarifies the RTP specification regard
ing the use of different clock rates in an RTP session. It also provides guidan
ce on how legacy RTP implementations that use multiple clock rates can interoper
ate with RTP implementations that use the algorithm described in this document.
It updates RFC 3550.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="7160"/>
<seriesInfo name="DOI" value="10.17487/RFC7160"/>
</reference>
<reference anchor="RFC7201" target="https://www.rfc-editor.org/info/rfc7
201" quoteTitle="true" derivedAnchor="RFC7201">
<front>
<title>Options for Securing RTP Sessions</title>
<author initials="M." surname="Westerlund" fullname="M. Westerlund">
<organization showOnFrontPage="true"/>
</author>
<author initials="C." surname="Perkins" fullname="C. Perkins">
<organization showOnFrontPage="true"/>
</author>
<date year="2014" month="April"/>
<abstract>
<t indent="0">The Real-time Transport Protocol (RTP) is used in a
large number of different application domains and environments. This heterogene
ity implies that different security mechanisms are needed to provide services su
ch as confidentiality, integrity, and source authentication of RTP and RTP Contr
ol Protocol (RTCP) packets suitable for the various environments. The range of
solutions makes it difficult for RTP-based application developers to pick the mo
st suitable mechanism. This document provides an overview of a number of securi
ty solutions for RTP and gives guidance for developers on how to choose the appr
opriate security mechanism.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="7201"/>
<seriesInfo name="DOI" value="10.17487/RFC7201"/>
</reference>
<reference anchor="RFC7656" target="https://www.rfc-editor.org/info/rfc7
656" quoteTitle="true" derivedAnchor="RFC7656">
<front>
<title>A Taxonomy of Semantics and Mechanisms for Real-Time Transpor
t Protocol (RTP) Sources</title>
<author initials="J." surname="Lennox" fullname="J. Lennox">
<organization showOnFrontPage="true"/>
</author>
<author initials="K." surname="Gross" fullname="K. Gross">
<organization showOnFrontPage="true"/>
</author>
<author initials="S." surname="Nandakumar" fullname="S. Nandakumar">
<organization showOnFrontPage="true"/>
</author>
<author initials="G." surname="Salgueiro" fullname="G. Salgueiro">
<organization showOnFrontPage="true"/>
</author>
<author initials="B." surname="Burman" fullname="B. Burman" role="ed
itor">
<organization showOnFrontPage="true"/>
</author>
<date year="2015" month="November"/>
<abstract>
<t indent="0">The terminology about, and associations among, Real-
time Transport Protocol (RTP) sources can be complex and somewhat opaque. This
document describes a number of existing and proposed properties and relationship
s among RTP sources and defines common terminology for discussing protocol entit
ies and their relationships.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="7656"/>
<seriesInfo name="DOI" value="10.17487/RFC7656"/>
</reference>
<reference anchor="RFC7657" target="https://www.rfc-editor.org/info/rfc7
657" quoteTitle="true" derivedAnchor="RFC7657">
<front>
<title>Differentiated Services (Diffserv) and Real-Time Communicatio
n</title>
<author initials="D." surname="Black" fullname="D. Black" role="edit
or">
<organization showOnFrontPage="true"/>
</author>
<author initials="P." surname="Jones" fullname="P. Jones">
<organization showOnFrontPage="true"/>
</author>
<date year="2015" month="November"/>
<abstract>
<t indent="0">This memo describes the interaction between Differen
tiated Services (Diffserv) network quality-of-service (QoS) functionality and re
al- time network communication, including communication based on the Real-time T
ransport Protocol (RTP). Diffserv is based on network nodes applying different
forwarding treatments to packets whose IP headers are marked with different Diff
serv Codepoints (DSCPs). WebRTC applications, as well as some conferencing appli
cations, have begun using the Session Description Protocol (SDP) bundle negotiat
ion mechanism to send multiple traffic streams with different QoS requirements u
sing the same network 5-tuple. The results of using multiple DSCPs to obtain di
fferent QoS treatments within a single network 5-tuple have transport protocol i
nteractions, particularly with congestion control functionality (e.g., reorderin
g). In addition, DSCP markings may be changed or removed between the traffic so
urce and destination. This memo covers the implications of these Diffserv aspec
ts for real-time network communication, including WebRTC.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="7657"/>
<seriesInfo name="DOI" value="10.17487/RFC7657"/>
</reference>
<reference anchor="RFC8829" target="https://www.rfc-editor.org/info/rfc8
829" quoteTitle="true" derivedAnchor="RFC8829">
<front>
<title>JavaScript Session Establishment Protocol (JSEP)</title>
<author initials="J." surname="Uberti" fullname="Justin Uberti">
<organization showOnFrontPage="true"/>
</author>
<author initials="C." surname="Jennings" fullname="Cullen Jennings">
<organization showOnFrontPage="true"/>
</author>
<author initials="E." surname="Rescorla" fullname="Eric Rescorla" ro
le="editor">
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8829"/>
<seriesInfo name="DOI" value="10.17487/RFC8829"/>
</reference>
<reference anchor="RFC8838" target="https://www.rfc-editor.org/info/rfc8
838" quoteTitle="true" derivedAnchor="RFC8838">
<front>
<title>Trickle ICE: Incremental Provisioning of Candidates for the I
nteractive Connectivity Establishment (ICE) Protocol</title>
<author initials="E" surname="Ivov" fullname="Emil Ivov">
<organization showOnFrontPage="true"/>
</author>
<author initials="J" surname="Uberti" fullname="Justin Uberti">
<organization showOnFrontPage="true"/>
</author>
<author initials="P" surname="Saint-Andre" fullname="Peter Saint-And
re">
<organization showOnFrontPage="true"/>
</author>
<date month="January" year="2021"/>
</front>
<seriesInfo name="RFC" value="8838"/>
<seriesInfo name="DOI" value="10.17487/RFC8838"/>
</reference>
</references> </references>
</references> </references>
<section toc="include" numbered="true" removeInRFC="false" pn="section-appen <section anchor="appendix">
dix.a"> <name>Design Considerations</name>
<name slugifiedName="name-design-considerations">Design Considerations</na <t>
me> One of the main issues regarding the BUNDLE grouping
<t indent="0" pn="section-appendix.a-1"> extensions has been whether, in offers and answers, the same
One of the main issues regarding the BUNDLE grouping extensions has been port value can be inserted in "m=" lines associated with a
whether, BUNDLE group, as the purpose of the extension is to negotiate
in offers and answers, the same port value can be inserted in "m=" the usage of a single transport for media specified by the
lines associated with a BUNDLE group, as the purpose of the extension is "m=" sections. Issues with both approaches, discussed in <xref
to negotiate target="appendix"/>, have been raised. The outcome was to
the usage of a single transport for media specified by the "m=" sections specify a mechanism that uses offers with both different and
. Issues identical port values.
with both approaches, discussed in the Appendix, have been raised. The o
utcome was to
specify a mechanism that uses offers with both different and identical p
ort values.
</t> </t>
<t indent="0" pn="section-appendix.a-2"> <t>
Below are the primary issues that have been considered when defining the "BUNDLE" Below are the primary issues that have been considered when defining the "BUNDLE"
grouping extension: grouping extension:
</t> </t>
<ol spacing="normal" type="%d)" indent="adaptive" start="1" pn="section-ap <ol type="%d)">
pendix.a-3"> <li>Interoperability with existing User Agents (UAs).</li>
<li pn="section-appendix.a-3.1" derivedCounter="1)">Interoperability wit <li>Interoperability with intermediary Back-to-Back User Agent (B2BUA) a
h existing User Agents (UAs).</li> nd proxy entities.</li>
<li pn="section-appendix.a-3.2" derivedCounter="2)">Interoperability wit <li>The number of ICE candidates and the time to gather them.</li>
h intermediary Back-to-Back User Agent (B2BUA) and proxy entities.</li> <li>Different error scenarios and when they occur.</li>
<li pn="section-appendix.a-3.3" derivedCounter="3)">Time to gather, and <li>SDP offer/answer impacts, including usage of port number value zero.
the number of, ICE candidates.</li> </li>
<li pn="section-appendix.a-3.4" derivedCounter="4)">Different error scen
arios and when they occur.</li>
<li pn="section-appendix.a-3.5" derivedCounter="5)">SDP offer/answer imp
acts, including usage of port number value zero.</li>
</ol> </ol>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a.1 <section>
"> <name>UA Interoperability</name>
<name slugifiedName="name-ua-interoperability">UA Interoperability</name <t>
>
<t indent="0" pn="section-a.1-1">
Consider the following SDP offer/answer exchange, where Alice sends an o ffer to Bob: Consider the following SDP offer/answer exchange, where Alice sends an o ffer to Bob:
</t> </t>
<t keepWithNext="true" indent="0" pn="section-a.1-2">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-a.1-3"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP4 atlanta.example.com o=alice 2890844526 2890844526 IN IP4 atlanta.example.com
s= s=
c=IN IP4 atlanta.example.com c=IN IP4 atlanta.example.com
t=0 0 t=0 0
m=audio 10000 RTP/AVP 97 m=audio 10000 RTP/AVP 97
a=rtpmap:97 iLBC/8000 a=rtpmap:97 iLBC/8000
m=video 10002 RTP/AVP 97 m=video 10002 RTP/AVP 97
a=rtpmap:97 H261/90000 a=rtpmap:97 H261/90000
</sourcecode> </sourcecode>
<t keepWithNext="true" indent="0" pn="section-a.1-4">SDP Answer</t> <t keepWithNext="true">SDP Answer</t>
<sourcecode type="sdp" markers="false" pn="section-a.1-5"> <sourcecode type="sdp">
v=0 v=0
o=bob 2808844564 2808844564 IN IP4 biloxi.example.com o=bob 2808844564 2808844564 IN IP4 biloxi.example.com
s= s=
c=IN IP4 biloxi.example.com c=IN IP4 biloxi.example.com
t=0 0 t=0 0
m=audio 20000 RTP/AVP 97 m=audio 20000 RTP/AVP 97
a=rtpmap:97 iLBC/8000 a=rtpmap:97 iLBC/8000
m=video 20002 RTP/AVP 97 m=video 20002 RTP/AVP 97
a=rtpmap:97 H261/90000 a=rtpmap:97 H261/90000
</sourcecode> </sourcecode>
<t indent="0" pn="section-a.1-6"> <t>
RFC 4961 specifies a way of doing symmetric RTP, but that is a later <xref target="RFC4961"/> specifies a way of doing symmetric RTP, but tha
extension to RTP, and Bob cannot assume that Alice supports RFC 4961. Th t is a later
is extension to RTP, and Bob cannot assume that Alice supports <xref target
="RFC4961"/>. This
means that Alice may be sending RTP from a different port than 10000 or means that Alice may be sending RTP from a different port than 10000 or
10002 -- some implementations simply send the RTP from an ephemeral 10002 -- some implementations simply send the RTP from an ephemeral
port. When Bob's endpoint receives an RTP packet, the only way that Bob port. When Bob's endpoint receives an RTP packet, the only way that Bob
knows if the packet is to be passed to the video or audio codec is by lo oking at knows if the packet is to be passed to the video or audio codec is by lo oking at
the port it was received on. the port it was received on.
This prompted some SDP implementations to use a port number as an index to find the This prompted some SDP implementations to use a port number as an index to find the
correct "m=" line in the SDP, since each "m"= section contains a differe nt port number. As a result, some correct "m=" line in the SDP, since each "m"= section contains a differe nt port number. As a result, some
implementations that do support symmetric RTP and ICE still use an SDP d ata implementations that do support symmetric RTP and ICE still use an SDP d ata
structure where SDP with "m=" sections with the same port such as: structure where SDP with "m=" sections with the same port such as:
</t> </t>
<t keepWithNext="true" indent="0" pn="section-a.1-7">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-a.1-8"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP4 atlanta.example.com o=alice 2890844526 2890844526 IN IP4 atlanta.example.com
s= s=
c=IN IP4 atlanta.example.com c=IN IP4 atlanta.example.com
t=0 0 t=0 0
m=audio 10000 RTP/AVP 97 m=audio 10000 RTP/AVP 97
a=rtpmap:97 iLBC/8000 a=rtpmap:97 iLBC/8000
m=video 10000 RTP/AVP 98 m=video 10000 RTP/AVP 98
a=rtpmap:98 H261/90000 a=rtpmap:98 H261/90000
</sourcecode> </sourcecode>
<t indent="0" pn="section-a.1-9"> <t>
will result in the second "m=" section being considered an SDP error will result in the second "m=" section being considered an SDP error
because it has the same port as the first line. because it has the same port as the first line.
</t> </t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a.2 <section>
"> <name>Usage of Port Number Value Zero</name>
<name slugifiedName="name-usage-of-port-number-value-">Usage of Port Num <t>
ber Value Zero</name>
<t indent="0" pn="section-a.2-1">
In an offer or answer, the media specified by an "m=" section can be In an offer or answer, the media specified by an "m=" section can be
disabled/rejected by setting the port number value to zero. This is diff erent disabled/rejected by setting the port number value to zero. This is diff erent
from, e.g., using the SDP direction attributes, where RTCP traffic will from, e.g., using the SDP direction attributes, where RTCP traffic will
continue even if the SDP 'inactive' attribute is indicated for the continue even if the SDP 'inactive' attribute is indicated for the
associated "m=" section. associated "m=" section.
</t> </t>
<t indent="0" pn="section-a.2-2"> <t>
If each "m=" section associated with a BUNDLE group would contain differ If each "m=" section associated with a BUNDLE group were to contain diff
ent erent
port values, and one of those port values would be used for a BUNDLE add port values and one of those port values were used for a BUNDLE address:
ress:port port
associated with the BUNDLE group, problems would occur if an endpoint wa nts to associated with the BUNDLE group, problems would occur if an endpoint wa nts to
disable/reject the "m=" section associated with that port, by setting th e port disable/reject the "m=" section associated with that port by setting the port
value to zero. After that, no "m=" section would contain the port value that value to zero. After that, no "m=" section would contain the port value that
is used for the BUNDLE address:port. In addition, it is unclear what wou ld happen is used for the BUNDLE address:port. In addition, it is unclear what wou ld happen
to the ICE candidates associated with the "m=" section, as they are also used for to the ICE candidates associated with the "m=" section, as they are also used for
the BUNDLE address:port. the BUNDLE address:port.
</t> </t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a.3 <section>
"> <name>B2BUA and Proxy Interoperability</name>
<name slugifiedName="name-b2bua-and-proxy-interoperab">B2BUA and Proxy I <t>
nteroperability</name>
<t indent="0" pn="section-a.3-1">
Some back-to-back user agents may be configured in a mode where if Some back-to-back user agents may be configured in a mode where if
the incoming call leg contains an SDP attribute the B2BUA does not the incoming call leg contains an SDP attribute the B2BUA does not
understand, the B2BUA still generates that SDP attribute in the offer understand, the B2BUA still generates that SDP attribute in the Offer
for the outgoing call leg. Consider a B2BUA that did not understand for the outgoing call leg. Consider a B2BUA that did not understand
the SDP 'rtcp' attribute, defined in RFC 3605, yet acted this way. the SDP 'rtcp' attribute, defined in <xref target="RFC3605"/>, yet acted this way.
Further, assume that the B2BUA was configured to tear down any call Further, assume that the B2BUA was configured to tear down any call
where it did not see any RTCP for 5 minutes. In this case, if the B2BUA where it did not see any RTCP for 5 minutes. In this case, if the B2BUA
received an offer like: received an Offer like:
</t> </t>
<t keepWithNext="true" indent="0" pn="section-a.3-2">SDP Offer</t> <t keepWithNext="true">SDP Offer</t>
<sourcecode type="sdp" markers="false" pn="section-a.3-3"> <sourcecode type="sdp">
v=0 v=0
o=alice 2890844526 2890844526 IN IP4 atlanta.example.com o=alice 2890844526 2890844526 IN IP4 atlanta.example.com
s= s=
c=IN IP4 atlanta.example.com c=IN IP4 atlanta.example.com
t=0 0 t=0 0
m=audio 49170 RTP/AVP 0 m=audio 49170 RTP/AVP 0
a=rtcp:53020 a=rtcp:53020
</sourcecode> </sourcecode>
<t indent="0" pn="section-a.3-4"> <t>
It would be looking for RTCP on port 49171 but would not see any it would be looking for RTCP on port 49171 but would not see any
because the RTCP would be on port 53020, and after five minutes, it would because the RTCP would be on port 53020, and after five minutes, it would
tear down the call. Similarly, a B2BUA that did not understand BUNDLE yet tear down the call. Similarly, a B2BUA that did not understand BUNDLE yet
put it in its offer may be looking for media on the wrong port and put it in its offer may be looking for media on the wrong port and
tear down the call. It is worth noting that a B2BUA that generated an tear down the call. It is worth noting that a B2BUA that generated an
offer with capabilities it does not understand is not compliant with the Offer with capabilities it does not understand is not compliant with the
specifications. specifications.
</t> </t>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a <section>
.3.1"> <name>Traffic Policing</name>
<name slugifiedName="name-traffic-policing">Traffic Policing</name> <t>
<t indent="0" pn="section-a.3.1-1">
Sometimes intermediaries do not act as B2BUAs, in the sense that Sometimes intermediaries do not act as B2BUAs, in the sense that
they don't modify SDP bodies nor do they terminate SIP dialogs. they don't modify SDP bodies nor do they terminate SIP dialogs.
However, they may still use SDP information (e.g., IP address and However, they may still use SDP information (e.g., IP address and
port) in order to control traffic gating functions and to set port) in order to control traffic gating functions and to set
traffic policing rules. There might be rules that will trigger traffic policing rules. There might be rules that will trigger
a session to be terminated in case media is not sent or received a session to be terminated in case media is not sent or received
on the ports retrieved from the SDP. This typically occurs once the on the ports retrieved from the SDP. This typically occurs once the
session is already established and ongoing. session is already established and ongoing.
</t> </t>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a <section>
.3.2"> <name>Bandwidth Allocation</name>
<name slugifiedName="name-bandwidth-allocation">Bandwidth Allocation</ <t>
name>
<t indent="0" pn="section-a.3.2-1">
Sometimes, intermediaries do not act as B2BUAs, in the sense that Sometimes, intermediaries do not act as B2BUAs, in the sense that
they don't modify SDP bodies nor do they terminate SIP dialogs. they don't modify SDP bodies nor do they terminate SIP dialogs.
However, they may still use SDP information (e.g., codecs and However, they may still use SDP information (e.g., codecs and
media types) in order to control bandwidth allocation functions. media types) in order to control bandwidth allocation functions.
The bandwidth allocation is done per "m=" section, which means that The bandwidth allocation is done per "m=" section, which means that
it might not be enough if media specified by all "m=" sections it might not be enough if media specified by all "m=" sections
try to use that bandwidth. That may simply lead to either bad try to use that bandwidth. That may simply lead to either a bad
user experience or termination of the call. user experience or termination of the call.
</t> </t>
</section> </section>
</section> </section>
<section toc="include" numbered="true" removeInRFC="false" pn="section-a.4 <section>
"> <name>Candidate Gathering</name>
<name slugifiedName="name-candidate-gathering">Candidate Gathering</name <t>
>
<t indent="0" pn="section-a.4-1">
When using ICE, a candidate needs to be gathered for each port. This When using ICE, a candidate needs to be gathered for each port. This
takes approximately 20 ms extra for each extra "m=" section due to the N AT takes approximately 20 ms extra for each extra "m=" section due to the N AT
pacing requirements. All of this gathering can be overlapped with other pacing requirements.
All of this gathering can be overlapped with other
things while, e.g., a web page is loading to minimize the impact. If the client things while, e.g., a web page is loading to minimize the impact. If the client
only wants to generate Traversal Using Relays around NAT (TURN) or STUN ICE candidates for one of the "m=" only wants to generate Traversal Using Relays around NAT (TURN) or STUN ICE candidates for one of the "m="
lines and then use Trickle ICE <xref target="RFC8838" format="default" s ectionFormat="of" derivedContent="RFC8838"/> lines and then use Trickle ICE <xref target="RFC8838"/>
to get the non-host ICE candidates for the rest of the "m=" sections, it <bcp14>MAY</bcp14> do to get the non-host ICE candidates for the rest of the "m=" sections, it <bcp14>MAY</bcp14> do
that and will not need any additional gathering time. that and will not need any additional gathering time.
</t> </t>
<t indent="0" pn="section-a.4-2"> <t>
Some people have suggested a TURN extension to get a bunch of TURN Some people have suggested a TURN extension to get a bunch of TURN
allocations at once. This would only provide a single STUN result, so in allocations at once. This would only provide a single STUN result, so in
cases where the other end did not support BUNDLE, it may cause more use of cases where the other end did not support BUNDLE, it may cause more use of
the TURN server, but it would be quick in the cases where both sides the TURN server, but it would be quick in the cases where both sides
supported BUNDLE and would fall back to a successful call in the other supported BUNDLE and would fall back to a successful call in the other
cases. cases.
</t> </t>
</section> </section>
<section anchor="sec-acks" toc="include" numbered="false" removeInRFC="fal </section>
se" pn="section-a.5"> <section anchor="sec-acks" numbered="false">
<name slugifiedName="name-acknowledgements">Acknowledgements</name> <name>Acknowledgements</name>
<t indent="0" pn="section-a.5-1"> <t>
The usage of the SDP grouping extension for negotiating bundled media is The usage of the SDP grouping extension for negotiating bundled media is
based on similar alternatives proposed by <contact fullname="Harald Alvestrand"/> and <contact fullname="Cullen Jennings"/>. The BUNDLE based on similar alternatives proposed by <contact fullname="Harald Alvestrand"/> and <contact fullname="Cullen Jennings"/>. The BUNDLE
extension described in this document is based on the different extension described in this document is based on the different
alternative proposals, and text (e.g., SDP examples) has been borrowed alternative proposals, and text (e.g., SDP examples) has been borrowed
(and, in some cases, modified) from those alternative proposals. (and, in some cases, modified) from those alternative proposals.
</t> </t>
<t indent="0" pn="section-a.5-2"> <t>
The SDP examples are also modified versions from the ones in the Alvestran d The SDP examples are also modified versions from the ones in the Alvestran d
proposal. proposal.
</t> </t>
<t indent="0" pn="section-a.5-3"> <t>
Thanks to <contact fullname="Paul Kyzivat"/>, <contact fullname="Martin Thanks to <contact fullname="Paul Kyzivat"/>, <contact fullname="Martin Th
Thomson"/>, <contact fullname="Flemming Andreasen"/>, <contact fullname="Tho omson"/>, <contact fullname="Flemming Andreasen"/>, <contact fullname="Thomas St
mas Stach"/>, <contact fullname="Ari Keranen"/>, <contact fullname="Adam Roach"/ ach"/>, <contact fullname="Ari Keränen"/>, <contact fullname="Adam Roach"/>, <co
>, <contact fullname="Christian Groves"/>, ntact fullname="Christian Groves"/>,
<contact fullname="Roman Shpount"/>, <contact fullname="Suhas Nandak umar"/>, <contact fullname="Nils Ohlmeier"/>, <contact fullname="Jens Guballa"/> , <contact fullname="Raju Makaraju"/>, <contact fullname="Justin Uberti"/>, <con tact fullname="Taylor Brandstetter"/>, <contact fullname="Roman Shpount"/>, <contact fullname="Suhas Nandak umar"/>, <contact fullname="Nils Ohlmeier"/>, <contact fullname="Jens Guballa"/> , <contact fullname="Raju Makaraju"/>, <contact fullname="Justin Uberti"/>, <con tact fullname="Taylor Brandstetter"/>,
<contact fullname="Byron Campen"/>, and <contact fullname="Eric Resc orla"/> for reading the text and providing useful feedback. <contact fullname="Byron Campen"/>, and <contact fullname="Eric Resc orla"/> for reading the text and providing useful feedback.
</t> </t>
<t indent="0" pn="section-a.5-4"> <t>
Thanks to <contact fullname="Bernard Aboba"/>, <contact fullname="Peter Thatcher"/>, <contact fullname="Justin Uberti"/>, and <contact fullname="Magnus Westerlund"/> for providing the text for the section on Thanks to <contact fullname="Bernard Aboba"/>, <contact fullname="Peter Thatcher"/>, <contact fullname="Justin Uberti"/>, and <contact fullname="Magnus Westerlund"/> for providing the text for the section on
RTP/RTCP stream association. RTP/RTCP stream association.
</t> </t>
<t indent="0" pn="section-a.5-5"> <t>
Thanks to <contact fullname="Magnus Westerlund"/>, <contact fullname="Coli n Perkins"/>, and <contact fullname="Jonathan Lennox"/> Thanks to <contact fullname="Magnus Westerlund"/>, <contact fullname="Coli n Perkins"/>, and <contact fullname="Jonathan Lennox"/>
for providing help and text on the RTP/RTCP procedures. for providing help and text on the RTP/RTCP procedures.
</t> </t>
<t indent="0" pn="section-a.5-6"> <t>
Thanks to <contact fullname="Charlie Kaufman"/> for performing the Sec-Di r review. Thanks to <contact fullname="Charlie Kaufman"/> for performing the Sec-Di r review.
</t> </t>
<t indent="0" pn="section-a.5-7"> <t>
Thanks to <contact fullname="Linda Dunbar"/> for performing the Gen-ART r eview. Thanks to <contact fullname="Linda Dunbar"/> for performing the Gen-ART r eview.
</t> </t>
<t indent="0" pn="section-a.5-8"> <t>
Thanks to Spotify for providing music for the countless hours of Thanks to Spotify for providing music for the countless hours of
document editing. document editing.
</t> </t>
</section>
</section>
<section anchor="authors-addresses" numbered="false" removeInRFC="false" toc
="include" pn="section-appendix.b">
<name slugifiedName="name-authors-addresses">Authors' Addresses</name>
<author initials="C." surname="Holmberg" fullname="Christer Holmberg">
<organization showOnFrontPage="true">Ericsson</organization>
<address>
<postal>
<street>Hirsalantie 11</street>
<code>02420</code>
<city>Jorvas</city>
<country>Finland</country>
</postal>
<email>christer.holmberg@ericsson.com</email>
</address>
</author>
<author fullname="Harald Tveit Alvestrand" initials="H." surname="Alvestra
nd">
<organization showOnFrontPage="true">Google</organization>
<address>
<postal>
<street>Kungsbron 2</street>
<city>Stockholm</city>
<code>11122</code>
<country>Sweden</country>
</postal>
<email>harald@alvestrand.no</email>
</address>
</author>
<author fullname="Cullen Jennings" initials="C." surname="Jennings">
<organization showOnFrontPage="true">Cisco</organization>
<address>
<postal>
<street>400 3rd Avenue SW, Suite 350</street>
<city>Calgary</city>
<region>AB</region>
<code>T2P 4H2</code>
<country>Canada</country>
</postal>
<email>fluffy@iii.ca</email>
</address>
</author>
</section> </section>
</back> </back>
</rfc> </rfc>
 End of changes. 504 change blocks. 
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