Diff: rfc8837xml2.original.xml

	rfc8837xml2.original.xml	rfc8837.xml

	<?xml version="1.0" encoding="US-ASCII"?>	<?xml version='1.0' encoding='utf-8'?>
	<!DOCTYPE rfc SYSTEM "rfc2629.dtd">	<rfc xmlns:xi="http://www.w3.org/2001/XInclude" version="3" category="std" conse
	<?rfc toc="yes"?>	nsus="true" docName="draft-ietf-tsvwg-rtcweb-qos-18" indexInclude="true" ipr="tr
	<?rfc tocompact="yes"?>	ust200902" number="8837" prepTime="2021-01-16T23:27:34" scripts="Common,Latin" s
	<?rfc tocdepth="3"?>	ortRefs="true" submissionType="IETF" symRefs="true" tocDepth="3" tocInclude="tru
	<?rfc tocindent="yes"?>	e" xml:lang="en">
	<?rfc symrefs="yes"?>	<link href="https://datatracker.ietf.org/doc/draft-ietf-tsvwg-rtcweb-qos-18" r
	<?rfc sortrefs="yes"?>	el="prev"/>
	<?rfc comments="yes"?>	<link href="https://dx.doi.org/10.17487/rfc8837" rel="alternate"/>
	<?rfc inline="yes"?>	<link href="urn:issn:2070-1721" rel="alternate"/>
	<?rfc compact="yes"?>
	<?rfc subcompact="no"?>

	<rfc category="std" docName="draft-ietf-tsvwg-rtcweb-qos-18"
	ipr="trust200902">

	<front>	<front>

	<title abbrev="WebRTC QoS">	<title abbrev="WebRTC QoS">Differentiated Services Code Point (DSCP) Packet
	DSCP Packet Markings for WebRTC QoS	Markings for WebRTC QoS</title>
	</title>	<seriesInfo name="RFC" value="8837" stream="IETF"/>

	<author fullname="Paul E. Jones" initials="P." surname="Jones">	<author fullname="Paul E. Jones" initials="P." surname="Jones">

	<organization>Cisco Systems</organization>	<organization showOnFrontPage="true">Cisco Systems</organization>
	<address>	<address>
	<email>paulej@packetizer.com</email>	<email>paulej@packetizer.com</email>
	</address>	</address>
	</author>	</author>


	<author fullname="Subha Dhesikan" initials="S." surname="Dhesikan">	<author fullname="Subha Dhesikan" initials="S." surname="Dhesikan">

	<organization>Cisco Systems</organization>	<organization showOnFrontPage="true">Individual</organization>
	<address>	<address>

	<email>sdhesika@cisco.com</email>	<email>sdhesikan@gmail.com</email>
	</address>	</address>
	</author>	</author>

		<author fullname="Cullen Jennings" initials="C." surname="Jennings">
	<author fullname="Cullen Jennings" initials="C."	<organization showOnFrontPage="true">Cisco Systems</organization>
	surname="Jennings">
	<organization>Cisco Systems</organization>
	<address>	<address>
	<email>fluffy@cisco.com</email>	<email>fluffy@cisco.com</email>
	</address>	</address>
	</author>	</author>


	<author fullname="Dan Druta" initials="D." surname="Druta">	<author fullname="Dan Druta" initials="D." surname="Druta">

	<organization>AT&T</organization>	<organization showOnFrontPage="true">AT&T</organization>
	<address>	<address>
	<email>dd5826@att.com</email>	<email>dd5826@att.com</email>
	</address>	</address>
	</author>	</author>

		<date month="01" year="2021"/>
	<date/>	<keyword>Diffserv</keyword>
		<keyword>rtcweb</keyword>
	<abstract>	<abstract pn="section-abstract">
	<t>	<t indent="0" pn="section-abstract-1">
	Many networks, such as service provider and enterprise networks,	Networks can provide different forwarding treatments for individual
	can provide different forwarding treatments for individual
	packets based on Differentiated Services Code Point (DSCP)	packets based on Differentiated Services Code Point (DSCP)
	values on a per-hop basis. This document provides the	values on a per-hop basis. This document provides the
	recommended DSCP values for web browsers to use for various	recommended DSCP values for web browsers to use for various

	classes of WebRTC traffic.	classes of Web Real-Time Communication (WebRTC) traffic.
	</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/rfc8837" 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>
		</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" keepWithNext="true" pn="section-toc.1-1.1.1"><xref der
		ivedContent="1" format="counter" sectionFormat="of" target="section-1"/>. <xref
		derivedContent="" format="title" sectionFormat="of" target="name-introduction">
		Introduction</xref></t>
		</li>
		<li pn="section-toc.1-1.2">
		<t indent="0" keepWithNext="true" pn="section-toc.1-1.2.1"><xref der
		ivedContent="2" format="counter" sectionFormat="of" target="section-2"/>. <xref
		derivedContent="" format="title" sectionFormat="of" target="name-terminology">T
		erminology</xref></t>
		</li>
		<li pn="section-toc.1-1.3">
		<t indent="0" keepWithNext="true" pn="section-toc.1-1.3.1"><xref der
		ivedContent="3" format="counter" sectionFormat="of" target="section-3"/>. <xref
		derivedContent="" format="title" sectionFormat="of" target="name-relation-to-ot
		her-specifica">Relation to Other Specifications</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-inputs">Inputs</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-dscp-mappings">DSCP Mappings</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-security-considerations">Security
		Considerations</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-iana-considerations">IANA Consider
		ations</xref></t>
		</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-downward-references">Downward Refe
		rences</xref></t>
		</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-references">References</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-normative-references">
		Normative References</xref></t>
		</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-informative-references
		">Informative References</xref></t>
		</li>
		</ul>
		</li>
		<li pn="section-toc.1-1.10">
		<t indent="0" pn="section-toc.1-1.10.1"><xref derivedContent="" form
		at="none" sectionFormat="of" target="section-appendix.a"/><xref derivedContent="
		" format="title" sectionFormat="of" target="name-acknowledgements">Acknowledgeme
		nts</xref></t>
		</li>
		<li pn="section-toc.1-1.11">
		<t indent="0" pn="section-toc.1-1.11.1"><xref derivedContent="" form
		at="none" sectionFormat="of" target="section-appendix.b"/><xref derivedContent="
		" format="title" sectionFormat="of" target="name-dedication">Dedication</xref></
		t>
		</li>
		<li pn="section-toc.1-1.12">
		<t indent="0" pn="section-toc.1-1.12.1"><xref derivedContent="" form
		at="none" sectionFormat="of" target="section-appendix.c"/><xref derivedContent="
		" format="title" sectionFormat="of" target="name-authors-addresses">Authors' Add
		resses</xref></t>
		</li>
		</ul>
		</section>
		</toc>
	</front>	</front>


	<middle>	<middle>

	<section title="Introduction">	<section numbered="true" toc="include" removeInRFC="false" pn="section-1">
	<t>	<name slugifiedName="name-introduction">Introduction</name>
	Differentiated Services Code Point (DSCP) <xref target="RFC2474"/>	<t indent="0" pn="section-1-1">
		Differentiated Services Code Point (DSCP) <xref target="RFC2474" format=
		"default" sectionFormat="of" derivedContent="RFC2474"/>
	packet marking can help provide QoS in some environments.	packet marking can help provide QoS in some environments.
	This specification provides default packet marking for browsers	This specification provides default packet marking for browsers
	that support WebRTC applications, but does not change any advice	that support WebRTC applications, but does not change any advice

	or requirements in other IETF RFCs. The contents of this	or requirements in other RFCs. The contents of this
	specification are intended to be a simple set of implementation	specification are intended to be a simple set of implementation

	recommendations based on the previous RFCs.	recommendations based on previous RFCs.
	</t>	</t>

		<t indent="0" pn="section-1-2">
	<t>	Networks in which these DSCP markings are beneficial (likely to
	Networks where these DSCP markings are beneficial (likely to
	improve QoS for WebRTC traffic) include:	improve QoS for WebRTC traffic) include:
	</t>	</t>

		<ol spacing="normal" type="1" indent="adaptive" start="1" pn="section-1-3"
	<t>	>
	<list style="numbers">	<li pn="section-1-3.1" derivedCounter="1.">
	<t>
	Private, wide-area networks. Network administrators have	Private, wide-area networks. Network administrators have
	control over remarking packets and treatment of packets.	control over remarking packets and treatment of packets.

	</t>	</li>
		<li pn="section-1-3.2" derivedCounter="2.">
	<t>
	Residential Networks. If the congested link is the	Residential Networks. If the congested link is the

	broadband uplink in a cable or DSL scenario, often	broadband uplink in a cable or DSL scenario, residential
	residential routers/NAT support preferential treatment based	routers/NAT often support preferential treatment based
	on DSCP.	on DSCP.

	</t>	</li>
		<li pn="section-1-3.3" derivedCounter="3.">
	<t>
	Wireless Networks. If the congested link is a local	Wireless Networks. If the congested link is a local
	wireless network, marking may help.	wireless network, marking may help.

	</t>	</li>
	</list>	</ol>
	</t>	<t indent="0" pn="section-1-4">
		There are cases where these DSCP markings do not help but,
	<t>	aside from possible priority inversion for "Less-than-Best-Effort
	There are cases where these DSCP markings do not help, but,	traffic" (see <xref target="dscp-mappings" format="default" sectionFormat
	aside from possible priority inversion for "less than best	="of" derivedContent="Section 5"/>), they seldom make things worse
	effort traffic" (see Section 5), they seldom make things worse
	if packets are marked appropriately.	if packets are marked appropriately.
	</t>	</t>

		<t indent="0" pn="section-1-5">
	<t>	DSCP values are, in principle, site specific with each site
	DSCP values are in principle site specific, with each site	selecting its own code points for controlling per-hop behavior
	selecting its own code points for controlling per-hop-behavior	to influence the QoS for transport-layer flows. However, in the
	to influence the QoS for transport-layer flows. However in the
	WebRTC use cases, the browsers need to set them to something	WebRTC use cases, the browsers need to set them to something

	when there is no site specific information. This document	when there is no site-specific information. This document
	describes a subset of DSCP code point values drawn from existing	describes a subset of DSCP code point values drawn from existing
	RFCs and common usage for use with WebRTC applications. These	RFCs and common usage for use with WebRTC applications. These
	code points are intended to be the default values used by a	code points are intended to be the default values used by a
	WebRTC application. While other values could be used, using a	WebRTC application. While other values could be used, using a
	non-default value may result in unexpected per-hop behavior. It	non-default value may result in unexpected per-hop behavior. It

	is RECOMMENDED that WebRTC applications use non-default values	is <bcp14>RECOMMENDED</bcp14> that WebRTC applications use non-default v alues
	only in private networks that are configured to use different	only in private networks that are configured to use different
	values.	values.
	</t>	</t>

		<t indent="0" pn="section-1-6">


	<t>
	This specification defines inputs that are provided by the	This specification defines inputs that are provided by the
	WebRTC application hosted in the browser that aid the browser in	WebRTC application hosted in the browser that aid the browser in
	determining how to set the various packet markings. The	determining how to set the various packet markings. The
	specification also defines the mapping from abstract QoS	specification also defines the mapping from abstract QoS
	policies (flow type, priority level) to those packet markings.	policies (flow type, priority level) to those packet markings.
	</t>	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-2">
	<section title="Terminology">	<name slugifiedName="name-terminology">Terminology</name>
	<t>	<t indent="0" pn="section-2-1">
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL	The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
	NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and	"<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>
	"OPTIONAL" in this document are to be interpreted as described	",
	in <xref target="RFC2119"/>.	"<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
		"<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
		"<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
		be
		interpreted as described in BCP 14 <xref target="RFC2119" format="default" s
		ectionFormat="of" derivedContent="RFC2119"/> <xref target="RFC8174" format="defa
		ult" sectionFormat="of" derivedContent="RFC8174"/> when, and only when, they app
		ear in all capitals, as
		shown here.
	</t>	</t>

		<t indent="0" pn="section-2-2">
	<t>
	The terms "browser" and "non-browser" are defined in	The terms "browser" and "non-browser" are defined in

	<xref target="RFC7742"/> and carry the same meaning in this	<xref target="RFC7742" format="default" sectionFormat="of" derivedConten t="RFC7742"/> and carry the same meaning in this
	document.	document.
	</t>	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-3">
	<section title="Relation to Other Specifications">	<name slugifiedName="name-relation-to-other-specifica">Relation to Other S
	<t>	pecifications</name>
	This document is a complement to <xref target="RFC7657"/>, which	<t indent="0" pn="section-3-1">
		This document is a complement to <xref target="RFC7657" format="default"
		sectionFormat="of" derivedContent="RFC7657"/>, which
	describes the interaction between DSCP and real-time	describes the interaction between DSCP and real-time
	communications. That RFC covers the implications of using	communications. That RFC covers the implications of using

	various DSCP values, particularly focusing on Real-time	various DSCP values, particularly focusing on the Real-time
	Transport Protocol (RTP) <xref target="RFC3550"/> streams that	Transport Protocol (RTP) <xref target="RFC3550" format="default" section
		Format="of" derivedContent="RFC3550"/> streams that
	are multiplexed onto a single transport-layer flow.	are multiplexed onto a single transport-layer flow.
	</t>	</t>

		<t indent="0" pn="section-3-2">
	<t>
	There are a number of guidelines specified in	There are a number of guidelines specified in

	<xref target="RFC7657"/> that apply to marking traffic sent by	<xref target="RFC7657" format="default" sectionFormat="of" derivedConten t="RFC7657"/> that apply to marking traffic sent by
	WebRTC applications, as it is common for multiple RTP streams to	WebRTC applications, as it is common for multiple RTP streams to
	be multiplexed on the same transport-layer flow. Generally, the	be multiplexed on the same transport-layer flow. Generally, the
	RTP streams would be marked with a value as appropriate from	RTP streams would be marked with a value as appropriate from

	<xref target="table-dscp"/>. A WebRTC application might also	<xref target="tab-dscp" format="default" sectionFormat="of" derivedConte nt="Table 1"/>. A WebRTC application might also
	multiplex data channel	multiplex data channel

	<xref target="I-D.ietf-rtcweb-data-channel"/> traffic over the	<xref target="RFC8831" format="default" sectionFormat="of" derivedConten
	same 5-tuple as RTP streams, which would also be marked as per	t="RFC8831"/> traffic over the
	that table. The guidance in <xref target="RFC7657"/> says that	same 5-tuple as RTP streams, which would also be marked per
		that table. The guidance in <xref target="RFC7657" format="default" sec
		tionFormat="of" derivedContent="RFC7657"/> says that
	all data channel traffic would be marked with a single value	all data channel traffic would be marked with a single value

	that is typically different than the value(s) used for RTP	that is typically different from the value(s) used for RTP
	streams multiplexed with the data channel traffic over the same	streams multiplexed with the data channel traffic over the same
	5-tuple, assuming RTP streams are marked with a value other than	5-tuple, assuming RTP streams are marked with a value other than

	default forwarding (DF). This is expanded upon further in the	Default Forwarding (DF). This is expanded upon further in the
	next section.	next section.
	</t>	</t>

		<t indent="0" pn="section-3-3">
	<t>
	This specification does not change or override the advice in any	This specification does not change or override the advice in any

	other IETF RFCs about setting packet markings. Rather, it	other RFCs about setting packet markings. Rather, it
	simply selects a subset of DSCP values that is relevant in the	simply selects a subset of DSCP values that is relevant in the
	WebRTC context.	WebRTC context.
	</t>	</t>

		<t indent="0" pn="section-3-4">
	<t>
	The DSCP value set by the endpoint is not trusted by the	The DSCP value set by the endpoint is not trusted by the
	network. In addition, the DSCP value may be remarked at any	network. In addition, the DSCP value may be remarked at any
	place in the network for a variety of reasons to any other DSCP	place in the network for a variety of reasons to any other DSCP

	value, including default forwarding (DF) value to provide basic	value, including the DF value to provide basic
	best effort service. Even so, there is benefit in marking	best-effort service. Even so, there is a benefit to marking
	traffic even if it only benefits the first few hops. The	traffic even if it only benefits the first few hops. The

	implications are discussed in Secton 3.2 of	implications are discussed in
	<xref target="RFC7657"/>. Further, a mitigation for such action	<xref target="RFC7657" sectionFormat="of" section="3.2" format="default"
		derivedLink="https://rfc-editor.org/rfc/rfc7657#section-3.2" derivedContent="RF
		C7657"/>. Further, a mitigation for such action
	is through an authorization mechanism. Such an authorization	is through an authorization mechanism. Such an authorization
	mechanism is outside the scope of this document.	mechanism is outside the scope of this document.
	</t>	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-4">
	<section title="Inputs">	<name slugifiedName="name-inputs">Inputs</name>
	<t>	<t indent="0" pn="section-4-1">
	WebRTC applications send and receive two types of flows of	This document recommends DSCP values for two classes of WebRTC flows:
	significance to this document:

	<list style="symbols">
	<t>
	media flows which are RTP streams
	<xref target="I-D.ietf-rtcweb-rtp-usage"/>
	</t>
	<t>
	data flows which are data channels
	<xref target="I-D.ietf-rtcweb-data-channel"/>
	</t>
	</list>
	</t>	</t>

		<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-4-2
	<t>	">
	Each of the RTP streams and distinct data channels consists of	<li pn="section-4-2.1">
		media flows that are RTP streams
		<xref target="RFC8834" format="default" sectionFormat="of" derivedCo
		ntent="RFC8834"/>
		</li>
		<li pn="section-4-2.2">
		data flows that are data channels
		<xref target="RFC8831" format="default" sectionFormat="of" derivedCo
		ntent="RFC8831"/>
		</li>
		</ul>
		<t indent="0" pn="section-4-3">
		Each of the RTP streams and distinct data channels consist of
	all of the packets associated with an independent media entity,	all of the packets associated with an independent media entity,
	so an RTP stream or distinct data channel is not always	so an RTP stream or distinct data channel is not always
	equivalent to a transport-layer flow defined by a 5-tuple	equivalent to a transport-layer flow defined by a 5-tuple
	(source address, destination address, source port, destination	(source address, destination address, source port, destination
	port, and protocol). There may be multiple RTP streams and data	port, and protocol). There may be multiple RTP streams and data
	channels multiplexed over the same 5-tuple, with each having a	channels multiplexed over the same 5-tuple, with each having a
	different level of importance to the application and, therefore,	different level of importance to the application and, therefore,
	potentially marked using different DSCP values than another RTP	potentially marked using different DSCP values than another RTP
	stream or data channel within the same transport-layer flow.	stream or data channel within the same transport-layer flow.
	(Note that there are restrictions with respect to marking	(Note that there are restrictions with respect to marking

	different data channels carried within the same SCTP association	different data channels carried within the same Stream Control
	as outlined in <xref target="dscp-mappings"/>.)	Transmission Protocol (SCTP) association
		as outlined in <xref target="dscp-mappings" format="default" sectionForm
		at="of" derivedContent="Section 5"/>.)
	</t>	</t>

		<t indent="0" pn="section-4-4">
	<t>
	The following are the inputs provided by the WebRTC application	The following are the inputs provided by the WebRTC application
	to the browser:	to the browser:


	<list style="symbols">	</t>
	<t>	<ul spacing="normal" bare="false" empty="false" indent="3" pn="section-4-5
		">
		<li pn="section-4-5.1">
	Flow Type: The application provides this input because it knows	Flow Type: The application provides this input because it knows

	if the flow is audio, interactive video <xref target="RFC4594"/>	if the flow is audio, interactive video (<xref target="RFC4594" form
	<xref target="G.1010"/> with or without audio, or data.	at="default" sectionFormat="of" derivedContent="RFC4594"/>
	</t>	<xref target="G.1010" format="default" sectionFormat="of" derivedConte
		nt="G.1010"/>) with or without audio, or data.
	<t>	</li>
		<li pn="section-4-5.2">
	Application Priority: Another input is the relative	Application Priority: Another input is the relative
	importance of an RTP stream or data channel. Many	importance of an RTP stream or data channel. Many

	applications have multiple flows of the same Flow Type and	applications have multiple flows of the same flow type and
	often some flows are more important than others. For	some flows are often more important than others. For
	example, in a video conference where there are usually audio	example, in a video conference where there are usually audio
	and video flows, the audio flow may be more important than	and video flows, the audio flow may be more important than
	the video flow. JavaScript applications can tell the	the video flow. JavaScript applications can tell the

	browser whether a particular flow is high, medium, low or	browser whether a particular flow is of High, Medium, Low, or
	very low importance to the application.	Very Low importance to the application.
	</t>	</li>
	</list>	</ul>
	</t>	<t indent="0" pn="section-4-6">
		<xref target="RFC8835" format="default" sectionFormat="of" derivedConten
	<t>	t="RFC8835"/> defines in more
	<xref target="I-D.ietf-rtcweb-transports"/> defines in more
	detail what an individual flow is within the WebRTC	detail what an individual flow is within the WebRTC
	context and priorities for media and data flows.	context and priorities for media and data flows.
	</t>	</t>

		<t indent="0" pn="section-4-7">
	<t>
	Currently in WebRTC, media sent over RTP is assumed to be	Currently in WebRTC, media sent over RTP is assumed to be

	interactive <xref target="I-D.ietf-rtcweb-transports"/> and	interactive <xref target="RFC8835" format="default" sectionFormat="of" d
	browser APIs do not exist to allow an application to to	erivedContent="RFC8835"/> and
		browser APIs do not exist to allow an application to
	differentiate between interactive and non-interactive video.	differentiate between interactive and non-interactive video.
	</t>	</t>
	</section>	</section>

		<section anchor="dscp-mappings" numbered="true" toc="include" removeInRFC="f
	<section anchor="dscp-mappings" title="DSCP Mappings">	alse" pn="section-5">
	<t>	<name slugifiedName="name-dscp-mappings">DSCP Mappings</name>
		<t indent="0" pn="section-5-1">
	The DSCP values for each flow type of interest to WebRTC based	The DSCP values for each flow type of interest to WebRTC based

	on application priority are shown in <xref target="table-dscp"/>.	on application priority are shown in <xref target="tab-dscp" format="def ault" sectionFormat="of" derivedContent="Table 1"/>.
	These values are based on the framework and recommended values in	These values are based on the framework and recommended values in

	<xref target="RFC4594"/>. A web browser SHOULD use these values	<xref target="RFC4594" format="default" sectionFormat="of" derivedConten
	to mark the appropriate media packets. More information on EF	t="RFC4594"/>. A web browser <bcp14>SHOULD</bcp14> use these values
	can be found in <xref target="RFC3246"/>. More information on	to mark the appropriate media packets. More information on Expedited
	AF can be found in <xref target="RFC2597"/>. DF is default	Forwarding (EF) and Assured Forwarding (AF) can be found in <xref target=
	forwarding which provides the basic best effort service	"RFC3246" format="default" sectionFormat="of" derivedContent="RFC3246"/> and <xr
	<xref target="RFC2474"/>.	ef target="RFC2597" format="default" sectionFormat="of" derivedContent="RFC2597"
		/>, respectively. DF is Default Forwarding, which provides the basic best-effor
		t service
		<xref target="RFC2474" format="default" sectionFormat="of" derivedConten
		t="RFC2474"/>.
	</t>	</t>

		<t indent="0" pn="section-5-2">
	<t>	WebRTC's use of multiple DSCP values may result in packets with
	WebRTC use of multiple DSCP values may encounter network blocking	certain DSCP values being blocked by a network. See
	of packets with certain DSCP values. See section 4.2 of	<xref target="RFC8835" sectionFormat="of" section="4.2" format="default"
	<xref target="I-D.ietf-rtcweb-transports"/> for further	derivedLink="https://rfc-editor.org/rfc/rfc8835#section-4.2" derivedContent="RF
		C8835"/> for further
	discussion, including how WebRTC implementations establish and	discussion, including how WebRTC implementations establish and
	maintain connectivity when such blocking is encountered.	maintain connectivity when such blocking is encountered.
	</t>	</t>

		<table anchor="tab-dscp" align="center" pn="table-1">
	<texttable anchor="table-dscp"	<name slugifiedName="name-recommended-dscp-values-for">Recommended DSCP
	title="Recommended DSCP Values for WebRTC Applications">	Values for WebRTC Applications</name>
	<ttcol align="center">Flow Type</ttcol>	<thead>
	<ttcol align="center">Very Low</ttcol>	<tr>
	<ttcol align="center">Low</ttcol>	<th align="center" colspan="1" rowspan="1">Flow Type</th>
	<ttcol align="center">Medium</ttcol>	<th align="center" colspan="1" rowspan="1">Very Low</th>
	<ttcol align="center">High</ttcol>	<th align="center" colspan="1" rowspan="1">Low</th>
	<c>Audio</c>	<th align="center" colspan="1" rowspan="1">Medium</th>
	<c>CS1 (8)</c>	<th align="center" colspan="1" rowspan="1">High</th>
	<c>DF (0)</c>	</tr>
	<c>EF (46)</c>	</thead>
	<c>EF (46)</c>	<tbody>
	<c> </c>	<tr>
	<c> </c>	<td align="center" colspan="1" rowspan="1">Audio</td>
	<c> </c>	<td align="center" colspan="1" rowspan="1">LE (1)</td>
	<c> </c>	<td align="center" colspan="1" rowspan="1">DF (0)</td>
	<c> </c>	<td align="center" colspan="1" rowspan="1">EF (46)</td>
	<c>Interactive Video with or without Audio</c>	<td align="center" colspan="1" rowspan="1">EF (46)</td>
	<c>CS1 (8)</c>	</tr>
	<c>DF (0)</c>	<tr>
	<c>AF42, AF43 (36, 38)</c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c>AF41, AF42 (34, 36)</c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c> </c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c> </c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c> </c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c> </c>	</tr>
	<c> </c>	<tr>
	<c>Non-Interactive Video with or without Audio</c>	<td align="center" colspan="1" rowspan="1">Interactive Video with or
	<c>CS1 (8)</c>	without Audio</td>
	<c>DF (0)</c>	<td align="center" colspan="1" rowspan="1">LE (1)</td>
	<c>AF32, AF33 (28, 30)</c>	<td align="center" colspan="1" rowspan="1">DF (0)</td>
	<c>AF31, AF32 (26, 28)</c>	<td align="center" colspan="1" rowspan="1">AF42, AF43 (36, 38)</td>
	<c> </c>	<td align="center" colspan="1" rowspan="1">AF41, AF42 (34, 36)</td>
	<c> </c>	</tr>
	<c> </c>	<tr>
	<c> </c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c> </c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c>Data</c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c>CS1 (8)</c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c>DF (0)</c>	<td align="center" colspan="1" rowspan="1"> </td>
	<c>AF11</c>	</tr>
	<c>AF21</c>	<tr>
	</texttable>	<td align="center" colspan="1" rowspan="1">Non-Interactive Video wit
		h or without Audio</td>
	<t>	<td align="center" colspan="1" rowspan="1">LE (1)</td>
	The application priority, indicated by the columns "very low",	<td align="center" colspan="1" rowspan="1">DF (0)</td>
	"low", "Medium", and "high", signifies the relative importance	<td align="center" colspan="1" rowspan="1">AF32, AF33 (28, 30)</td>
		<td align="center" colspan="1" rowspan="1">AF31, AF32 (26, 28)</td>
		</tr>
		<tr>
		<td align="center" colspan="1" rowspan="1"> </td>
		<td align="center" colspan="1" rowspan="1"> </td>
		<td align="center" colspan="1" rowspan="1"> </td>
		<td align="center" colspan="1" rowspan="1"> </td>
		<td align="center" colspan="1" rowspan="1"> </td>
		</tr>
		<tr>
		<td align="center" colspan="1" rowspan="1">Data</td>
		<td align="center" colspan="1" rowspan="1">LE (1)</td>
		<td align="center" colspan="1" rowspan="1">DF (0)</td>
		<td align="center" colspan="1" rowspan="1">AF11</td>
		<td align="center" colspan="1" rowspan="1">AF21</td>
		</tr>
		</tbody>
		</table>
		<t indent="0" pn="section-5-4">
		The application priority, indicated by the columns "Very Low",
		"Low", "Medium", and "High", signifies the relative importance
	of the flow within the application. It is an input that the	of the flow within the application. It is an input that the
	browser receives to assist in selecting the DSCP value and	browser receives to assist in selecting the DSCP value and
	adjusting the network transport behavior.	adjusting the network transport behavior.
	</t>	</t>

		<t indent="0" pn="section-5-5">
	<t>	The above table assumes that packets marked with LE are treated as
	The above table assumes that packets marked with CS1 are treated	lower effort (i.e., "less than best effort"), such as the LE behavior
	as "less than best effort", such as the LE behavior described in	described in <xref target="RFC8622" format="default" sectionFormat="of" deriv
	<xref target="RFC3662"/>. However, the treatment of CS1 is	edContent="RFC8622"/>. However, the treatment of LE is
	implementation dependent. If an implementation treats CS1 as	implementation dependent. If an implementation treats LE as other
	other than "less than best effort", then the actual priority	than "less than best effort", then the actual priority (or, more
	(or, more precisely, the per-hop-behavior) of the packets may be	precisely, the per-hop behavior) of the packets may be changed from
	changed from what is intended. It is common for CS1 to be	what is intended. It is common for LE to be treated the same as DF,
	treated the same as DF, so applications and browsers using CS1	so applications and browsers using LE cannot assume that LE will be
	cannot assume that CS1 will be treated differently than DF	treated differently than DF <xref target="RFC7657" format="default" sectionFo
	<xref target="RFC7657"/>. However, it is also possible per	rmat="of" derivedContent="RFC7657"/>. During development of this
	<xref target="RFC2474"/> for CS1 traffic to be given better	document, the CS1 DSCP was recommended for "very low" application
	treatment than DF, thus caution should be exercised when	priority traffic; implementations that followed that recommendation
	electing to use CS1. This is one of the cases where marking	<bcp14>SHOULD</bcp14> be updated to use the LE DSCP instead of the CS1 DSCP.
	packets using these recommendations can make things worse.
	</t>	</t>

		<t indent="0" pn="section-5-6">
	<t>
	Implementers should also note that excess EF traffic is dropped.	Implementers should also note that excess EF traffic is dropped.
	This could mean that a packet marked as EF may not get through,	This could mean that a packet marked as EF may not get through,
	although the same packet marked with a different DSCP value would	although the same packet marked with a different DSCP value would
	have gotten through. This is not a flaw, but how excess EF	have gotten through. This is not a flaw, but how excess EF
	traffic is intended to be treated.	traffic is intended to be treated.
	</t>	</t>

		<t indent="0" pn="section-5-7">
	<t>	The browser <bcp14>SHOULD</bcp14> first select the flow type of the flow
	The browser SHOULD first select the flow type of the flow.	.
	Within the flow type, the relative importance of the flow	Within the flow type, the relative importance of the flow

	SHOULD be used to select the appropriate DSCP value.	<bcp14>SHOULD</bcp14> be used to select the appropriate DSCP value.
	</t>	</t>

		<t indent="0" pn="section-5-8">
	<t>
	Currently, all WebRTC video is assumed to be interactive	Currently, all WebRTC video is assumed to be interactive

	<xref target="I-D.ietf-rtcweb-transports"/>, for which the	<xref target="RFC8835" format="default" sectionFormat="of" derivedConten
	Interactive Video DSCP values in Table 1 SHOULD be used.	t="RFC8835"/>, for which the
	Browsers MUST NOT use the AF3x DSCP values (for Non-Interactive	interactive video DSCP values in Table 1 <bcp14>SHOULD</bcp14> be used.
	Video in Table 1) for WebRTC applications. Non-browser	Browsers <bcp14>MUST NOT</bcp14> use the AF3x DSCP values (for non-inter
	implementations of WebRTC MAY use the AF3x DSCP values for video	active
		video in Table 1) for WebRTC applications. Non-browser
		implementations of WebRTC <bcp14>MAY</bcp14> use the AF3x DSCP values fo
		r video
	that is known not to be interactive, e.g., all video in a WebRTC	that is known not to be interactive, e.g., all video in a WebRTC
	video playback application that is not implemented in a	video playback application that is not implemented in a
	browser.	browser.
	</t>	</t>

		<t indent="0" pn="section-5-9">
	<t>
	The combination of flow type and application priority provides	The combination of flow type and application priority provides
	specificity and helps in selecting the right DSCP value for the	specificity and helps in selecting the right DSCP value for the

	flow. All packets within a flow SHOULD have the same application	flow. All packets within a flow <bcp14>SHOULD</bcp14> have the same app lication
	priority. In some cases, the selected application priority cell	priority. In some cases, the selected application priority cell
	may have multiple DSCP values, such as AF41 and AF42. These offer	may have multiple DSCP values, such as AF41 and AF42. These offer
	different drop precedences. The different drop precedence	different drop precedences. The different drop precedence

	values provides additional granularity in classifying packets	values provide additional granularity in classifying packets
	within a flow. For example, in a video conference the video	within a flow. For example, in a video conference, the video
	flow may have medium application priority, thus either AF42 or	flow may have medium application priority, thus either AF42 or
	AF43 may be selected. More important video packets (e.g., a	AF43 may be selected. More important video packets (e.g., a
	video picture or frame encoded without any dependency on any	video picture or frame encoded without any dependency on any
	prior pictures or frames) might be marked with AF42 and less	prior pictures or frames) might be marked with AF42 and less
	important packets (e.g., a video picture or frame encoded based	important packets (e.g., a video picture or frame encoded based
	on the content of one or more prior pictures or frames) might be	on the content of one or more prior pictures or frames) might be
	marked with AF43 (e.g., receipt of the more important packets	marked with AF43 (e.g., receipt of the more important packets
	enables a video renderer to continue after one or more packets	enables a video renderer to continue after one or more packets
	are lost).	are lost).
	</t>	</t>

		<t indent="0" pn="section-5-10">
	<t>
	It is worth noting that the application priority is utilized by	It is worth noting that the application priority is utilized by
	the coupled congestion control mechanism for media flows per	the coupled congestion control mechanism for media flows per

	<xref target="I-D.ietf-rmcat-coupled-cc"/> and the SCTP	<xref target="RFC8699" format="default" sectionFormat="of" derivedConten t="RFC8699"/> and the SCTP
	scheduler for data channel traffic per	scheduler for data channel traffic per

	<xref target="I-D.ietf-rtcweb-data-channel"/>.	<xref target="RFC8831" format="default" sectionFormat="of" derivedConten t="RFC8831"/>.
	</t>	</t>

		<t indent="0" pn="section-5-11">
	<t>	For reasons discussed in
	For reasons discussed in Section 6 of	<xref target="RFC7657" sectionFormat="of" section="6" format="default" d
	<xref target="RFC7657"/>, if multiple flows are multiplexed	erivedLink="https://rfc-editor.org/rfc/rfc7657#section-6" derivedContent="RFC765
	using a reliable transport (e.g., TCP) then all of the packets	7"/>, if multiple flows are multiplexed
	for all flows multiplexed over that transport-layer flow MUST be	using a reliable transport (e.g., TCP), then all of the packets
		for all flows multiplexed over that transport-layer flow <bcp14>MUST</bc
		p14> be
	marked using the same DSCP value. Likewise, all WebRTC data	marked using the same DSCP value. Likewise, all WebRTC data

	channel packets transmitted over an SCTP association MUST be	channel packets transmitted over an SCTP association <bcp14>MUST</bcp14> be
	marked using the same DSCP value, regardless of how many data	marked using the same DSCP value, regardless of how many data
	channels (streams) exist or what kind of traffic is carried over	channels (streams) exist or what kind of traffic is carried over
	the various SCTP streams. In the event that the browser wishes	the various SCTP streams. In the event that the browser wishes

	to change the DSCP value in use for an SCTP association, it MUST	to change the DSCP value in use for an SCTP association, it <bcp14>MUST< /bcp14>
	reset the SCTP congestion controller after changing values.	reset the SCTP congestion controller after changing values.

	Frequent changes in the DSCP value used for an SCTP association	However, frequent changes in the DSCP value used for an SCTP association
	are discouraged, though, as this would defeat any attempts at	are discouraged, as this would defeat any attempts at
	effectively managing congestion. It should also be noted that	effectively managing congestion. It should also be noted that
	any change in DSCP value that results in a reset of the	any change in DSCP value that results in a reset of the
	congestion controller puts the SCTP association back into slow	congestion controller puts the SCTP association back into slow
	start, which may have undesirable effects on application	start, which may have undesirable effects on application
	performance.	performance.
	</t>	</t>

		<t indent="0" pn="section-5-12">
	<t>
	For the data channel traffic multiplexed over an SCTP	For the data channel traffic multiplexed over an SCTP

	association, it is RECOMMENDED that the DSCP value selected be	association, it is <bcp14>RECOMMENDED</bcp14> that the DSCP value select ed be
	the one associated with the highest priority requested for all	the one associated with the highest priority requested for all
	data channels multiplexed over the SCTP association. Likewise,	data channels multiplexed over the SCTP association. Likewise,
	when multiplexing multiple flows over a TCP connection,	when multiplexing multiple flows over a TCP connection,

	the DCSP value selected should be the one associated with the	the DSCP value selected <bcp14>SHOULD</bcp14> be the one associated with the
	highest priority requested for all multiplexed flows.	highest priority requested for all multiplexed flows.
	</t>	</t>

		<t indent="0" pn="section-5-13">
	<t>	If a packet enters a network that has no support for a flow-type-applica
	If a packet enters a network that has no support for a flow	tion priority combination specified in
	type-application priority combination specified in	<xref target="tab-dscp" format="default" sectionFormat="of" derivedConte
	<xref target="table-dscp"/>, then the network node at the edge	nt="Table 1"/>, then the network node at the edge
	will remark the DSCP value based on policies. This could result	will remark the DSCP value based on policies. This could result
	in the flow not getting the network treatment it expects based	in the flow not getting the network treatment it expects based
	on the original DSCP value in the packet. Subsequently, if the	on the original DSCP value in the packet. Subsequently, if the
	packet enters a network that supports a larger number of these	packet enters a network that supports a larger number of these
	combinations, there may not be sufficient information in the	combinations, there may not be sufficient information in the
	packet to restore the original markings. Mechanisms for	packet to restore the original markings. Mechanisms for
	restoring such original DSCP is outside the scope of this	restoring such original DSCP is outside the scope of this
	document.	document.
	</t>	</t>

		<t indent="0" pn="section-5-14">
	<t>
	In summary, DSCP marking provides neither guarantees nor	In summary, DSCP marking provides neither guarantees nor
	promised levels of service. However, DSCP marking is expected	promised levels of service. However, DSCP marking is expected
	to provide a statistical improvement in real-time service as a	to provide a statistical improvement in real-time service as a
	whole. The service provided to a packet is dependent upon the	whole. The service provided to a packet is dependent upon the
	network design along the path, as well as the network conditions	network design along the path, as well as the network conditions
	at every hop.	at every hop.
	</t>	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-6">
	<section title="Security Considerations">	<name slugifiedName="name-security-considerations">Security Considerations
	<t>	</name>
		<t indent="0" pn="section-6-1">
	Since the JavaScript application specifies the flow type and	Since the JavaScript application specifies the flow type and
	application priority that determine the media flow DSCP values	application priority that determine the media flow DSCP values
	used by the browser, the browser could consider application use	used by the browser, the browser could consider application use
	of a large number of higher priority flows to be suspicious.	of a large number of higher priority flows to be suspicious.
	If the server hosting the JavaScript application is compromised,	If the server hosting the JavaScript application is compromised,
	many browsers within the network might simultaneously transmit	many browsers within the network might simultaneously transmit

	flows with the same DSCP marking. The DiffServ architecture	flows with the same DSCP marking. The Diffserv architecture
	requires ingress traffic conditioning for reasons that include	requires ingress traffic conditioning for reasons that include
	protecting the network from this sort of attack.	protecting the network from this sort of attack.
	</t>	</t>

		<t indent="0" pn="section-6-2">
	<t>
	Otherwise, this specification does not add any additional	Otherwise, this specification does not add any additional
	security implications beyond those addressed in the following	security implications beyond those addressed in the following
	DSCP-related specifications. For security implications on use	DSCP-related specifications. For security implications on use

	of DSCP, please refer to Section 7 of <xref target="RFC7657"/>	of DSCP, please refer to <xref target="RFC7657" sectionFormat="of" secti
	and Section 6 of <xref target="RFC4594"/>. Please also see	on="7" format="default" derivedLink="https://rfc-editor.org/rfc/rfc7657#section-
	<xref target="I-D.ietf-rtcweb-security"/> as an additional	7" derivedContent="RFC7657"/>
		and <xref target="RFC4594" sectionFormat="of" section="6" format="defaul
		t" derivedLink="https://rfc-editor.org/rfc/rfc4594#section-6" derivedContent="RF
		C4594"/>. Please also see
		<xref target="RFC8826" format="default" sectionFormat="of" derivedConten
		t="RFC8826"/> as an additional
	reference.	reference.
	</t>	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-7">
	<section title="IANA Considerations">	<name slugifiedName="name-iana-considerations">IANA Considerations</name>
	<t>	<t indent="0" pn="section-7-1">This document has no IANA actions.</t>
	This specification does not require any actions from IANA.
	</t>
	</section>	</section>

		<section numbered="true" toc="include" removeInRFC="false" pn="section-8">
	<section title="Downward References">	<name slugifiedName="name-downward-references">Downward References</name>
	<t>	<t indent="0" pn="section-8-1">
	This specification contains a downwards reference to	This specification contains downwards references to
	<xref target="RFC4594"/> and <xref target="RFC7657"/>. However,	<xref target="RFC4594" format="default" sectionFormat="of" derivedConten
	the parts of the former RFC used by this specification are	t="RFC4594"/> and <xref target="RFC7657" format="default" sectionFormat="of" der
	sufficiently stable for this downward reference. The guidance	ivedContent="RFC7657"/>. However,
		the parts of the former RFCs used by this specification are
		sufficiently stable for these downward references. The guidance
	in the latter RFC is necessary to understand the Diffserv	in the latter RFC is necessary to understand the Diffserv
	technology used in this document and the motivation	technology used in this document and the motivation
	for the recommended DSCP values and procedures.	for the recommended DSCP values and procedures.
	</t>	</t>
	</section>	</section>

		</middle>
	<section title="Acknowledgements">	<back>
	<t>	<references pn="section-9">
	Thanks to David Black, Magnus Westerlund, Paolo Severini, Jim	<name slugifiedName="name-references">References</name>
	Hasselbrook, Joe Marcus, Erik Nordmark, Michael Tuexen, and	<references pn="section-9.1">
	Brian Carpenter for their invaluable input.	<name slugifiedName="name-normative-references">Normative References</na
		me>
		<reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2
		119" quoteTitle="true" derivedAnchor="RFC2119">
		<front>
		<title>Key words for use in RFCs to Indicate Requirement Levels</tit
		le>
		<author initials="S." surname="Bradner" fullname="S. Bradner">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="1997" month="March"/>
		<abstract>
		<t indent="0">In many standards track documents several words are
		used to signify the requirements in the specification. These words are often ca
		pitalized. This document defines these words as they should be interpreted in IE
		TF documents. This document specifies an Internet Best Current Practices for th
		e Internet Community, and requests discussion and suggestions for improvements.<
		/t>
		</abstract>
		</front>
		<seriesInfo name="BCP" value="14"/>
		<seriesInfo name="RFC" value="2119"/>
		<seriesInfo name="DOI" value="10.17487/RFC2119"/>
		</reference>
		<reference anchor="RFC4594" target="https://www.rfc-editor.org/info/rfc4
		594" quoteTitle="true" derivedAnchor="RFC4594">
		<front>
		<title>Configuration Guidelines for DiffServ Service Classes</title>
		<author initials="J." surname="Babiarz" fullname="J. Babiarz">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="K." surname="Chan" fullname="K. Chan">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="F." surname="Baker" fullname="F. Baker">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="2006" month="August"/>
		<abstract>
		<t indent="0">This document describes service classes configured w
		ith Diffserv and recommends how they can be used and how to construct them using
		Differentiated Services Code Points (DSCPs), traffic conditioners, Per-Hop Beha
		viors (PHBs), and Active Queue Management (AQM) mechanisms. There is no intrins
		ic requirement that particular DSCPs, traffic conditioners, PHBs, and AQM be use
		d for a certain service class, but as a policy and for interoperability it is us
		eful to apply them consistently. This memo provides information for the Interne
		t community.</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="4594"/>
		<seriesInfo name="DOI" value="10.17487/RFC4594"/>
		</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="RFC7742" target="https://www.rfc-editor.org/info/rfc7
		742" quoteTitle="true" derivedAnchor="RFC7742">
		<front>
		<title>WebRTC Video Processing and Codec Requirements</title>
		<author initials="A.B." surname="Roach" fullname="A.B. Roach">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="2016" month="March"/>
		<abstract>
		<t indent="0">This specification provides the requirements and con
		siderations for WebRTC applications to send and receive video across a network.
		It specifies the video processing that is required as well as video codecs and
		their parameters.</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="7742"/>
		<seriesInfo name="DOI" value="10.17487/RFC7742"/>
		</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="RFC8622" target="https://www.rfc-editor.org/info/rfc8
		622" quoteTitle="true" derivedAnchor="RFC8622">
		<front>
		<title>A Lower-Effort Per-Hop Behavior (LE PHB) for Differentiated S
		ervices</title>
		<author initials="R." surname="Bless" fullname="R. Bless">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="2019" month="June"/>
		<abstract>
		<t indent="0">This document specifies properties and characteristi
		cs of a Lower- Effort Per-Hop Behavior (LE PHB). The primary objective of this
		LE PHB is to protect Best-Effort (BE) traffic (packets forwarded with the defaul
		t PHB) from LE traffic in congestion situations, i.e., when resources become sca
		rce, BE traffic has precedence over LE traffic and may preempt it. Alternativel
		y, packets forwarded by the LE PHB can be associated with a scavenger service cl
		ass, i.e., they scavenge otherwise-unused resources only. There are numerous us
		es for this PHB, e.g., for background traffic of low precedence, such as bulk da
		ta transfers with low priority in time, non-time-critical backups, larger softwa
		re updates, web search engines while gathering information from web servers and
		so on. This document recommends a standard Differentiated Services Code Point (
		DSCP) value for the LE PHB.</t>
		<t indent="0">This specification obsoletes RFC 3662 and updates th
		e DSCP recommended in RFCs 4594 and 8325 to use the DSCP assigned in this specif
		ication.</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="8622"/>
		<seriesInfo name="DOI" value="10.17487/RFC8622"/>
		</reference>
		<reference anchor="RFC8826" target="https://www.rfc-editor.org/info/rfc8
		826" quoteTitle="true" derivedAnchor="RFC8826">
		<front>
		<title>Security Considerations for WebRTC</title>
		<author initials="E." surname="Rescorla" fullname="Eric Rescorla">
		<organization showOnFrontPage="true"/>
		</author>
		<date month="January" year="2021"/>
		</front>
		<seriesInfo name="RFC" value="8826"/>
		<seriesInfo name="DOI" value="10.17487/RFC8826"/>
		</reference>
		<reference anchor="RFC8831" target="https://www.rfc-editor.org/info/rfc8
		831" quoteTitle="true" derivedAnchor="RFC8831">
		<front>
		<title>WebRTC Data Channels</title>
		<author initials="R" surname="Jesup" fullname="Randell Jesup">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="S" surname="Loreto" fullname="Salvatore Loreto">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="M" surname="Tüxen" fullname="Michael Tüxen">
		<organization showOnFrontPage="true"/>
		</author>
		<date month="January" year="2021"/>
		</front>
		<seriesInfo name="RFC" value="8831"/>
		<seriesInfo name="DOI" value="10.17487/RFC8831"/>
		</reference>
		<reference anchor="RFC8834" target="https://www.rfc-editor.org/info/rfc8
		834" quoteTitle="true" derivedAnchor="RFC8834">
		<front>
		<title>Media Transport and Use of RTP in WebRTC</title>
		<author initials="C." surname="Perkins" fullname="Colin Perkins">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="M." surname="Westerlund" fullname="Magnus Westerlu
		nd">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="J." surname="Ott" fullname="Jörg Ott">
		<organization showOnFrontPage="true"/>
		</author>
		<date month="January" year="2021"/>
		</front>
		<seriesInfo name="RFC" value="8834"/>
		<seriesInfo name="DOI" value="10.17487/RFC8834"/>
		</reference>
		<reference anchor="RFC8835" target="https://www.rfc-editor.org/info/rfc8
		835" quoteTitle="true" derivedAnchor="RFC8835">
		<front>
		<title>Transports for WebRTC</title>
		<author initials="H." surname="Alvestrand" fullname="Harald Alvestra
		nd">
		<organization showOnFrontPage="true"/>
		</author>
		<date month="January" year="2021"/>
		</front>
		<seriesInfo name="RFC" value="8835"/>
		<seriesInfo name="DOI" value="10.17487/RFC8835"/>
		</reference>
		</references>
		<references pn="section-9.2">
		<name slugifiedName="name-informative-references">Informative References
		</name>
		<reference anchor="G.1010" target="https://www.itu.int/rec/T-REC-G.1010-
		200111-I/en" quoteTitle="true" derivedAnchor="G.1010">
		<front>
		<title>End-user multimedia QoS categories</title>
		<author>
		<organization showOnFrontPage="true">ITU-T</organization>
		</author>
		<date month="November" year="2001"/>
		</front>
		<seriesInfo name="ITU-T Recommendation" value="G.1010"/>
		</reference>
		<reference anchor="RFC2474" target="https://www.rfc-editor.org/info/rfc2
		474" quoteTitle="true" derivedAnchor="RFC2474">
		<front>
		<title>Definition of the Differentiated Services Field (DS Field) in
		the IPv4 and IPv6 Headers</title>
		<author initials="K." surname="Nichols" fullname="K. Nichols">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="S." surname="Blake" fullname="S. Blake">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="F." surname="Baker" fullname="F. Baker">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="D." surname="Black" fullname="D. Black">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="1998" month="December"/>
		<abstract>
		<t indent="0">This document defines the IP header field, called th
		e DS (for differentiated services) field. [STANDARDS-TRACK]</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="2474"/>
		<seriesInfo name="DOI" value="10.17487/RFC2474"/>
		</reference>
		<reference anchor="RFC2597" target="https://www.rfc-editor.org/info/rfc2
		597" quoteTitle="true" derivedAnchor="RFC2597">
		<front>
		<title>Assured Forwarding PHB Group</title>
		<author initials="J." surname="Heinanen" fullname="J. Heinanen">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="F." surname="Baker" fullname="F. Baker">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="W." surname="Weiss" fullname="W. Weiss">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="J." surname="Wroclawski" fullname="J. Wroclawski">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="1999" month="June"/>
		<abstract>
		<t indent="0">This document defines a general use Differentiated S
		ervices (DS) Per-Hop-Behavior (PHB) Group called Assured Forwarding (AF). [STAND
		ARDS-TRACK]</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="2597"/>
		<seriesInfo name="DOI" value="10.17487/RFC2597"/>
		</reference>
		<reference anchor="RFC3246" target="https://www.rfc-editor.org/info/rfc3
		246" quoteTitle="true" derivedAnchor="RFC3246">
		<front>
		<title>An Expedited Forwarding PHB (Per-Hop Behavior)</title>
		<author initials="B." surname="Davie" fullname="B. Davie">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="A." surname="Charny" fullname="A. Charny">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="J.C.R." surname="Bennet" fullname="J.C.R. Bennet">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="K." surname="Benson" fullname="K. Benson">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="J.Y." surname="Le Boudec" fullname="J.Y. Le Boudec
		">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="W." surname="Courtney" fullname="W. Courtney">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="S." surname="Davari" fullname="S. Davari">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="V." surname="Firoiu" fullname="V. Firoiu">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="D." surname="Stiliadis" fullname="D. Stiliadis">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="2002" month="March"/>
		<abstract>
		<t indent="0">This document defines a PHB (per-hop behavior) calle
		d Expedited Forwarding (EF). The PHB is a basic building block in the Different
		iated Services architecture. EF is intended to provide a building block for low
		delay, low jitter and low loss services by ensuring that the EF aggregate is se
		rved at a certain configured rate. This document obsoletes RFC 2598. [STANDARDS
		-TRACK]</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="3246"/>
		<seriesInfo name="DOI" value="10.17487/RFC3246"/>
		</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="RFC8699" target="https://www.rfc-editor.org/info/rfc8
		699" quoteTitle="true" derivedAnchor="RFC8699">
		<front>
		<title>Coupled Congestion Control for RTP Media</title>
		<author initials="S." surname="Islam" fullname="S. Islam">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="M." surname="Welzl" fullname="M. Welzl">
		<organization showOnFrontPage="true"/>
		</author>
		<author initials="S." surname="Gjessing" fullname="S. Gjessing">
		<organization showOnFrontPage="true"/>
		</author>
		<date year="2020" month="January"/>
		<abstract>
		<t indent="0">When multiple congestion-controlled Real-time Transp
		ort Protocol (RTP) sessions traverse the same network bottleneck, combining thei
		r controls can improve the total on-the-wire behavior in terms of delay, loss, a
		nd fairness. This document describes such a method for flows that have the same
		sender, in a way that is as flexible and simple as possible while minimizing the
		number of changes needed to existing RTP applications. This document also speci
		fies how to apply the method for the Network-Assisted Dynamic Adaptation (NADA)
		congestion control algorithm and provides suggestions on how to apply it to othe
		r congestion control algorithms.</t>
		</abstract>
		</front>
		<seriesInfo name="RFC" value="8699"/>
		<seriesInfo name="DOI" value="10.17487/RFC8699"/>
		</reference>
		</references>
		</references>
		<section numbered="false" toc="include" removeInRFC="false" pn="section-appe
		ndix.a">
		<name slugifiedName="name-acknowledgements">Acknowledgements</name>
		<t indent="0" pn="section-appendix.a-1">
		Thanks to <contact fullname="David Black"/>, <contact fullname="Magnus
		Westerlund"/>, <contact fullname="Paolo Severini"/>, <contact fullname="Jim
		Hasselbrook"/>, <contact fullname="Joe Marcus"/>, <contact fullname="Erik N
		ordmark"/>, <contact fullname="Michael Tüxen"/>, and
		<contact fullname="Brian Carpenter"/> for their invaluable input.
	</t>	</t>
	</section>	</section>

		<section numbered="false" toc="include" removeInRFC="false" pn="section-appe
	<section title="Dedication">	ndix.b">
	<t>	<name slugifiedName="name-dedication">Dedication</name>
	This document is dedicated to the memory of James Polk, a	<t indent="0" pn="section-appendix.b-1">
		This document is dedicated to the memory of <contact fullname="James Pol
		k"/>, a
	long-time friend and colleague. James made important	long-time friend and colleague. James made important
	contributions to this specification, including serving initially	contributions to this specification, including serving initially
	as one of the primary authors. The IETF global community mourns	as one of the primary authors. The IETF global community mourns
	his loss and he will be missed dearly.	his loss and he will be missed dearly.
	</t>	</t>
	</section>	</section>

		<section anchor="authors-addresses" numbered="false" removeInRFC="false" toc
	<section title="Document History">	="include" pn="section-appendix.c">
	<t>	<name slugifiedName="name-authors-addresses">Authors' Addresses</name>
	Note to RFC Editor: Please remove this section.	<author fullname="Paul E. Jones" initials="P." surname="Jones">
	</t>	<organization showOnFrontPage="true">Cisco Systems</organization>
		<address>
	<t>	<email>paulej@packetizer.com</email>
	This document was originally an individual submission in RTCWeb WG.	</address>
	The RTCWeb working group selected it to be become a WG document.	</author>
	Later the transport ADs requested that this be moved to the TSVWG WG	<author fullname="Subha Dhesikan" initials="S." surname="Dhesikan">
	as that seemed to be a better match.	<organization showOnFrontPage="true">Individual</organization>
	</t>	<address>
		<email>sdhesikan@gmail.com</email>
		</address>
		</author>
		<author fullname="Cullen Jennings" initials="C." surname="Jennings">
		<organization showOnFrontPage="true">Cisco Systems</organization>
		<address>
		<email>fluffy@cisco.com</email>
		</address>
		</author>
		<author fullname="Dan Druta" initials="D." surname="Druta">
		<organization showOnFrontPage="true">AT&T</organization>
		<address>
		<email>dd5826@att.com</email>
		</address>
		</author>
	</section>	</section>


	</middle>

	<back>
	<references title="Normative References">
	<?rfc include='reference.RFC.4594'?>
	<?rfc include='reference.RFC.2119'?>
	<?rfc include='reference.RFC.7657'?>
	<?rfc include='reference.RFC.7742'?>
	<?rfc include='reference.I-D.ietf-rtcweb-security'?>
	<?rfc include='reference.I-D.ietf-rtcweb-transports'?>
	<?rfc include='reference.I-D.ietf-rtcweb-rtp-usage'?>
	<?rfc include='reference.I-D.ietf-rtcweb-data-channel'?>
	</references>

	<references title="Informative References">
	<?rfc include='reference.RFC.2474'?>
	<?rfc include='reference.RFC.2597'?>
	<?rfc include='reference.RFC.3246'?>
	<?rfc include='reference.RFC.3550'?>
	<?rfc include='reference.RFC.3662'?>
	<?rfc include='reference.I-D.ietf-rmcat-coupled-cc'?>
	<reference anchor="G.1010">
	<front>
	<title>End-user multimedia QoS categories</title>
	<author>
	<organization>International Telecommunications Union</organization>
	</author>
	<date month="November" year="2001"/>
	</front>
	<seriesInfo name="Recommendation" value="ITU-T G.1010"/>
	</reference>
	</references>
	</back>	</back>
	</rfc>	</rfc>

End of changes. 89 change blocks.
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