rfc8866v7.txt		rfc8866.txt
	Internet Engineering Task Force (IETF) A. Begen		Internet Engineering Task Force (IETF) A. Begen
	Request for Comments: 8866 Networked Media		Request for Comments: 8866 Networked Media
	Obsoletes: 4566 P. Kyzivat		Obsoletes: 4566 P. Kyzivat
	Category: Standards Track		Category: Standards Track
	ISSN: 2070-1721 C. Perkins		ISSN: 2070-1721 C. Perkins
	University of Glasgow		University of Glasgow
	M. Handley		M. Handley
	UCL		UCL
	July 2020		August 2020
	SDP: Session Description Protocol		SDP: Session Description Protocol
	Abstract		Abstract
	This memo defines the Session Description Protocol (SDP). SDP is		This memo defines the Session Description Protocol (SDP). SDP is
	intended for describing multimedia sessions for the purposes of		intended for describing multimedia sessions for the purposes of
	session announcement, session invitation, and other forms of		session announcement, session invitation, and other forms of
	multimedia session initiation. This document obsoletes RFC 4566.		multimedia session initiation. This document obsoletes RFC 4566.
	skipping to change at line 2069 ¶		skipping to change at line 2069 ¶
	8.2.4. Attribute Names (<attribute-name>)		8.2.4. Attribute Names (<attribute-name>)
	Attribute-field names (<attribute-name>) MUST be registered with IANA		Attribute-field names (<attribute-name>) MUST be registered with IANA
	and documented to avoid any issues due to conflicting attribute		and documented to avoid any issues due to conflicting attribute
	definitions under the same name. (While unknown attributes in SDP		definitions under the same name. (While unknown attributes in SDP
	are simply ignored, conflicting ones that fragment the protocol are a		are simply ignored, conflicting ones that fragment the protocol are a
	serious problem.)		serious problem.)
	The format of the attribute registry is:		The format of the attribute registry is:
	+======+================+=============+==============+===========+		+======+==========+=============+==============+===========+
	| Type | Attribute Name | Usage Level | Mux Category | Reference |		| Type | SDP Name | Usage Level | Mux Category | Reference |
	+======+================+=============+==============+===========+		+======+==========+=============+==============+===========+
	Table 4: Format of the attribute registry		Table 4: Format of the attribute registry
	For example, the attribute "setup", which is defined for both session		For example, the attribute "setup", which is defined for both session
	and media level, will be listed in the new registry as follows:		and media level, will be listed in the new registry as follows:
	+===========+=======+=============+===========+=====================+		+===========+======+==========+===========+========================+
	| Type | SDP | Usage | Mux | Reference |		| Type | SDP | Usage | Mux | Reference |
	| | Name | Level | Category | |		| | Name | Level | Category | |
	+===========+=======+=============+===========+=====================+		+===========+======+==========+===========+========================+
	| attribute | setup | session, | TRANSPORT | [RFC4145] [RFC8859] |		| attribute | lang | session, | TRANSPORT | RFC 8866 [RFC8859] |
	| | | media, | | [MSRP-DATACHANNEL] |		| | | media | | |
	| | | dcsa | | |		+-----------+------+----------+-----------+------------------------+
	| | | (msrp) | | |
	+-----------+-------+-------------+-----------+---------------------+
	Table 5: Attribute registry example		Table 5: Attribute registry example
	This one registry combines all of the previous usage-level-specific		This one registry combines all of the previous usage-level-specific
	<attribute-name> registries, including updates made by [RFC8859].		<attribute-name> registries, including updates made by [RFC8859].
	IANA is requested to do the necessary reformatting.		IANA is requested to do the necessary reformatting.
	Section 6 of this document replaces the initial set of attribute		Section 6 of this document replaces the initial set of attribute
	definitions made by [RFC4566]. IANA is requested to update the		definitions made by [RFC4566]. IANA is requested to update the
	registry accordingly.		registry accordingly.
	Documents can define new attributes and can also extend the		Documents can define new attributes and can also extend the
	skipping to change at line 2474 ¶		skipping to change at line 2472 ¶
	base64-char = ALPHA / DIGIT / "+" / "/"		base64-char = ALPHA / DIGIT / "+" / "/"
	; sub-rules of 'a='		; sub-rules of 'a='
	attribute = (attribute-name ":" attribute-value) /		attribute = (attribute-name ":" attribute-value) /
	attribute-name		attribute-name
	attribute-name = token		attribute-name = token
	attribute-value = byte-string		attribute-value = byte-string
			att-field = attribute-name ; for backward compatibility
	; sub-rules of 'm='		; sub-rules of 'm='
	media = token		media = token
	;typically "audio", "video", "text", "image"		;typically "audio", "video", "text", "image"
	;or "application"		;or "application"
	fmt = token		fmt = token
	;typically an RTP payload type for audio		;typically an RTP payload type for audio
	;and video media		;and video media
	proto = token *("/" token)		proto = token *("/" token)
	;typically "RTP/AVP", "RTP/"SAVP, or "udp"		;typically "RTP/AVP", "RTP/SAVP", "udp",
			;or "RTP/SAVPF"
	port = 1*DIGIT		port = 1*DIGIT
	; generic sub-rules: addressing		; generic sub-rules: addressing
	unicast-address = IP4-address / IP6-address / FQDN / extn-addr		unicast-address = IP4-address / IP6-address / FQDN / extn-addr
	multicast-address = IP4-multicast / IP6-multicast / FQDN		multicast-address = IP4-multicast / IP6-multicast / FQDN
	/ extn-addr		/ extn-addr
	IP4-multicast = m1 3( "." decimal-uchar )		IP4-multicast = m1 3( "." decimal-uchar )
	skipping to change at line 2784 ¶		skipping to change at line 2785 ¶
	<https://www.rfc-editor.org/rfc/rfc8864>.		<https://www.rfc-editor.org/rfc/rfc8864>.
	11.2. Informative References		11.2. Informative References
	[ITU.H332.1998]		[ITU.H332.1998]
	International Telecommunication Union, "H.332 : H.323		International Telecommunication Union, "H.332 : H.323
	extended for loosely coupled conferences", ITU		extended for loosely coupled conferences", ITU
	Recommendation H.332, September 1998,		Recommendation H.332, September 1998,
	<https://www.itu.int/rec/T-REC-H.332-199809-I/en>.		<https://www.itu.int/rec/T-REC-H.332-199809-I/en>.
	[MSRP-DATACHANNEL]
	Recio, J. and C. Holmberg, "MSRP over Data Channels", Work
	in Progress, Internet-Draft, draft-ietf-mmusic-msrp-usage-
	data-channel-21, 7 July 2020,
	<https://tools.ietf.org/html/draft-ietf-mmusic-msrp-usage-
	data-channel-21>.
	[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail		[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
	Extensions (MIME) Part One: Format of Internet Message		Extensions (MIME) Part One: Format of Internet Message
	Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,		Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
	<https://www.rfc-editor.org/info/rfc2045>.		<https://www.rfc-editor.org/info/rfc2045>.
	[RFC2327] Handley, M. and V. Jacobson, "SDP: Session Description		[RFC2327] Handley, M. and V. Jacobson, "SDP: Session Description
	Protocol", RFC 2327, DOI 10.17487/RFC2327, April 1998,		Protocol", RFC 2327, DOI 10.17487/RFC2327, April 1998,
	<https://www.rfc-editor.org/info/rfc2327>.		<https://www.rfc-editor.org/info/rfc2327>.
	[RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session		[RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session
	skipping to change at line 2851 ¶		skipping to change at line 2845 ¶
	"Indicating User Agent Capabilities in the Session		"Indicating User Agent Capabilities in the Session
	Initiation Protocol (SIP)", RFC 3840,		Initiation Protocol (SIP)", RFC 3840,
	DOI 10.17487/RFC3840, August 2004,		DOI 10.17487/RFC3840, August 2004,
	<https://www.rfc-editor.org/info/rfc3840>.		<https://www.rfc-editor.org/info/rfc3840>.
	[RFC3890] Westerlund, M., "A Transport Independent Bandwidth		[RFC3890] Westerlund, M., "A Transport Independent Bandwidth
	Modifier for the Session Description Protocol (SDP)",		Modifier for the Session Description Protocol (SDP)",
	RFC 3890, DOI 10.17487/RFC3890, September 2004,		RFC 3890, DOI 10.17487/RFC3890, September 2004,
	<https://www.rfc-editor.org/info/rfc3890>.		<https://www.rfc-editor.org/info/rfc3890>.
	[RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in
	the Session Description Protocol (SDP)", RFC 4145,
	DOI 10.17487/RFC4145, September 2005,
	<https://www.rfc-editor.org/info/rfc4145>.
	[RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session		[RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session
	Description Protocol (SDP) Security Descriptions for Media		Description Protocol (SDP) Security Descriptions for Media
	Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006,		Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006,
	<https://www.rfc-editor.org/info/rfc4568>.		<https://www.rfc-editor.org/info/rfc4568>.
	[RFC4855] Casner, S., "Media Type Registration of RTP Payload		[RFC4855] Casner, S., "Media Type Registration of RTP Payload
	Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,		Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
	<https://www.rfc-editor.org/info/rfc4855>.		<https://www.rfc-editor.org/info/rfc4855>.
	[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,		[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
End of changes. 8 change blocks.
	27 lines changed or deleted		16 lines changed or added
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