draft-ietf-mmusic-rfc4566bis-17.txt   draft-ietf-mmusic-rfc4566bis-18.txt 
Network Working Group M. Handley Network Working Group M. Handley
Internet-Draft UCL Internet-Draft UCL
Obsoletes: 4566 (if approved) V. Jacobson Obsoletes: 4566 (if approved) V. Jacobson
Intended status: Standards Track PARC Intended status: Standards Track PARC
Expires: December 24, 2016 C. Perkins Expires: August 8, 2017 C. Perkins
University of Glasgow University of Glasgow
A. Begen A. Begen
Networked Media Networked Media
June 22, 2016 February 4, 2017
SDP: Session Description Protocol SDP: Session Description Protocol
draft-ietf-mmusic-rfc4566bis-17 draft-ietf-mmusic-rfc4566bis-18
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.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 24, 2016. This Internet-Draft will expire on August 8, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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6.7.1. recvonly (receive-only) . . . . . . . . . . . . . . . 31 6.7.1. recvonly (receive-only) . . . . . . . . . . . . . . . 31
6.7.2. sendrecv (send-receive) . . . . . . . . . . . . . . . 31 6.7.2. sendrecv (send-receive) . . . . . . . . . . . . . . . 31
6.7.3. sendonly (send-only) . . . . . . . . . . . . . . . . 32 6.7.3. sendonly (send-only) . . . . . . . . . . . . . . . . 32
6.7.4. inactive . . . . . . . . . . . . . . . . . . . . . . 32 6.7.4. inactive . . . . . . . . . . . . . . . . . . . . . . 32
6.8. orient (orientation) . . . . . . . . . . . . . . . . . . 33 6.8. orient (orientation) . . . . . . . . . . . . . . . . . . 33
6.9. type (conference type) . . . . . . . . . . . . . . . . . 33 6.9. type (conference type) . . . . . . . . . . . . . . . . . 33
6.10. charset (character set) . . . . . . . . . . . . . . . . . 34 6.10. charset (character set) . . . . . . . . . . . . . . . . . 34
6.11. sdplang (SDP language) . . . . . . . . . . . . . . . . . 35 6.11. sdplang (SDP language) . . . . . . . . . . . . . . . . . 35
6.12. lang (language) . . . . . . . . . . . . . . . . . . . . . 36 6.12. lang (language) . . . . . . . . . . . . . . . . . . . . . 36
6.13. framerate (frame rate) . . . . . . . . . . . . . . . . . 37 6.13. framerate (frame rate) . . . . . . . . . . . . . . . . . 37
6.14. quality . . . . . . . . . . . . . . . . . . . . . . . . . 37 6.14. quality . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.15. fmtp (format parameters) . . . . . . . . . . . . . . . . 38 6.15. fmtp (format parameters) . . . . . . . . . . . . . . . . 38
7. Security Considerations . . . . . . . . . . . . . . . . . . . 39 7. Security Considerations . . . . . . . . . . . . . . . . . . . 39
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
8.1. The "application/sdp" Media Type . . . . . . . . . . . . 41 8.1. The "application/sdp" Media Type . . . . . . . . . . . . 41
8.2. Registration of Parameters . . . . . . . . . . . . . . . 43 8.2. Registration of Parameters . . . . . . . . . . . . . . . 43
8.2.1. Media Types ("media") . . . . . . . . . . . . . . . . 43 8.2.1. Media Types ("media") . . . . . . . . . . . . . . . . 43
8.2.2. Transport Protocols ("proto") . . . . . . . . . . . . 43 8.2.2. Transport Protocols ("proto") . . . . . . . . . . . . 43
8.2.3. Media Formats ("fmt") . . . . . . . . . . . . . . . . 44 8.2.3. Media Formats ("fmt") . . . . . . . . . . . . . . . . 44
8.2.4. Attribute Names ("att-field") . . . . . . . . . . . . 44 8.2.4. Attribute Names ("att-field") . . . . . . . . . . . . 44
8.2.5. Bandwidth Specifiers ("bwtype") . . . . . . . . . . . 47 8.2.5. Bandwidth Specifiers ("bwtype") . . . . . . . . . . . 47
8.2.6. Network Types ("nettype") . . . . . . . . . . . . . . 47 8.2.6. Network Types ("nettype") . . . . . . . . . . . . . . 47
8.2.7. Address Types ("addrtype") . . . . . . . . . . . . . 48 8.2.7. Address Types ("addrtype") . . . . . . . . . . . . . 48
8.2.8. Registration Procedure . . . . . . . . . . . . . . . 48 8.2.8. Registration Procedure . . . . . . . . . . . . . . . 48
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5.14. Media Descriptions ("m=") 5.14. Media Descriptions ("m=")
m=<media> <port> <proto> <fmt> ... m=<media> <port> <proto> <fmt> ...
A session description may contain a number of media descriptions. A session description may contain a number of media descriptions.
Each media description starts with an "m=" line and is terminated by Each media description starts with an "m=" line and is terminated by
either the next "m=" line or by the end of the session description. either the next "m=" line or by the end of the session description.
A media field has several sub-fields: A media field has several sub-fields:
<media> is the media type. Currently defined media are "audio", <media> is the media type. This document defines the values
"video", "text", "application", and "message", although this list "audio", "video", "text", "application", and "message". This list
may be extended in the future (see Section 8). is extended and may be further extended by other memos registering
media types in the future (see Section 8).
<port> is the transport port to which the media stream is sent. The <port> is the transport port to which the media stream is sent. The
meaning of the transport port depends on the network being used as meaning of the transport port depends on the network being used as
specified in the relevant "c=" line, and on the transport protocol specified in the relevant "c=" line, and on the transport protocol
defined in the <proto> sub-field of the media field. Other ports defined in the <proto> sub-field of the media field. Other ports
used by the media application (such as the RTP Control Protocol used by the media application (such as the RTP Control Protocol
(RTCP) port [RFC3550]) MAY be derived algorithmically from the (RTCP) port [RFC3550]) MAY be derived algorithmically from the
base media port or MAY be specified in a separate attribute (for base media port or MAY be specified in a separate attribute (for
example, "a=rtcp:" as defined in [RFC3605]). example, "a=rtcp:" as defined in [RFC3605]).
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Syntax: Syntax:
lang-value = Language-Tag lang-value = Language-Tag
; Language-Tag defined in RFC5646 ; Language-Tag defined in RFC5646
Example: Example:
a=lang:de a=lang:de
Multiple lang attributes can be provided either at session or media Multiple lang attributes can be provided either at session or media
level if the session or media has capabilities to use multiple level if the session or media has capabilities in more than one
languages, in which case the order of the attributes indicates the language, in which case the order of the attributes indicates the
order of preference of the various languages in the session or media, order of preference of the various languages in the session or media,
from most preferred to least preferred. from most preferred to least preferred.
As a session-level attribute, lang specifies a language capability As a session-level attribute, lang specifies a language capability
for the session being described. As a media-level attribute, it for the session being described. As a media-level attribute, it
specifies a language capability for that media, overriding any specifies a language capability for that media, overriding any
session-level language(s) specified. session-level language(s) specified.
The "lang" attribute value must be a single [RFC5646] language tag in The "lang" attribute value must be a single [RFC5646] language tag in
US-ASCII. A "lang" attribute SHOULD be specified when a session is US-ASCII. A "lang" attribute SHOULD be specified when a session is
of sufficient scope to cross geographic boundaries where the language of sufficient scope to cross geographic boundaries where the language
of recipients cannot be assumed, or where the session has of participants cannot be assumed, or where the session has
capabilities in languages different from the locally assumed norm. capabilities in languages different from the locally assumed norm.
Events during the session can influence which language(s) are used, The "lang" attribute is supposed to be used for settling the initial
and the participants are not strictly bound to only use the declared language(s) used in the session. Events during the session may
languages. influence which language(s) are used, and the participants are not
strictly bound to only use the declared languages.
Most real-time use cases start with just one language used, while
other cases involve a range of languages, e.g. an interpreted or
subtitled session. When more than one 'lang' attribute is specified,
the "lang" attribute itself does not provide any information about if
multiple languages are intended to be used during the session, or if
the intention is to only select one language. Other attributes or
the semantics in which the "lang" attributes are used might indicate
such conditions. Without such indications of usage intent, it is
assumed that for a negotiated session one of the declared languages
will be selected and used.
6.13. framerate (frame rate) 6.13. framerate (frame rate)
Name: framerate Name: framerate
Value: framerate-value Value: framerate-value
Usage Level: media Usage Level: media
Charset Dependent: no Charset Dependent: no
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Updated attribute registrations are accepted according to the Updated attribute registrations are accepted according to the
"Specification Required" policy of [RFC5226], provided that the "Specification Required" policy of [RFC5226], provided that the
specification updating the attribute (for example, by adding a new specification updating the attribute (for example, by adding a new
value) considers the registration information items from value) considers the registration information items from
Section Section 8.2.4.1 according to the following bullets: Section Section 8.2.4.1 according to the following bullets:
o Contact Name: A name MUST be provided. o Contact Name: A name MUST be provided.
o Contact Email Address: An email address MUST be provided. o Contact Email Address: An email address MUST be provided.
o Attribute Name: MUST be provided and MUST not be changed. o Attribute Name: MUST be provided and MUST NOT be changed.
Otherwise it is a new attribute. Otherwise it is a new attribute.
o Attribute Syntax: The existing rule syntax with the syntax o Attribute Syntax: The existing rule syntax with the syntax
extensions MUST be provided if there is a change to the syntax. A extensions MUST be provided if there is a change to the syntax. A
revision to an existing attribute usage MAY extend the syntax of revision to an existing attribute usage MAY extend the syntax of
an attribute, but MUST be backward compatible. an attribute, but MUST be backward compatible.
o Attribute Semantics: A semantic description of new additional o Attribute Semantics: A semantic description of new additional
attributes values or a semantic extension of existing values. attributes values or a semantic extension of existing values.
Existing attribute values semantics MUST only be extended in a Existing attribute values semantics MUST only be extended in a
backward compatible manner. backward compatible manner.
o Usage Level: Updates MAY only add additional levels. o Usage Level: Updates MAY only add additional levels.
o Charset Dependent: MUST not be changed. o Charset Dependent: MUST NOT be changed.
o Purpose: MAY be extended according to the updated usage. o Purpose: MAY be extended according to the updated usage.
o O/A Procedures: MAY be updated in a backward compatible manner o O/A Procedures: MAY be updated in a backward compatible manner
and/or it applies to a new usage level only. and/or it applies to a new usage level only.
o Mux Category: No change unless from TBD to another value. It MAY o Mux Category: No change unless from TBD to another value. It MAY
also change if 'media' level is being added to the definition of also change if 'media' level is being added to the definition of
an attribute that previously did not include it. an attribute that previously did not include it.
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; sub-rules of 'a=' ; sub-rules of 'a='
attribute = (att-field ":" att-value) / att-field attribute = (att-field ":" att-value) / att-field
att-field = token att-field = token
att-value = byte-string att-value = byte-string
; sub-rules of 'm=' ; sub-rules of 'm='
media = token media = token
;typically "audio", "video", "text", or ;typically "audio", "video", "text", "image"
;"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" or "udp" ;typically "RTP/AVP" or "udp"
port = 1*DIGIT port = 1*DIGIT
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(SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009, (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009,
<http://www.rfc-editor.org/info/rfc5576>. <http://www.rfc-editor.org/info/rfc5576>.
[I-D.iana-charset-reg-procedure] [I-D.iana-charset-reg-procedure]
McFadden, M. and A. Melnikov, "IANA Charset Registration McFadden, M. and A. Melnikov, "IANA Charset Registration
Procedures", draft-iana-charset-reg-procedure-01 (work in Procedures", draft-iana-charset-reg-procedure-01 (work in
progress), April 2015. progress), April 2015.
[I-D.ietf-mmusic-sdp-mux-attributes] [I-D.ietf-mmusic-sdp-mux-attributes]
Nandakumar, S., "A Framework for SDP Attributes when Nandakumar, S., "A Framework for SDP Attributes when
Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-12 Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16
(work in progress), January 2016. (work in progress), December 2016.
[I-D.ietf-mmusic-data-channel-sdpneg] [I-D.ietf-mmusic-data-channel-sdpneg]
Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R., Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R.,
and J. Marcon, "SDP-based Data Channel Negotiation", and J. Marcon, "SDP-based Data Channel Negotiation",
draft-ietf-mmusic-data-channel-sdpneg-08 (work in draft-ietf-mmusic-data-channel-sdpneg-11 (work in
progress), February 2016. progress), January 2017.
12.2. Informative References 12.2. Informative References
[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,
<http://www.rfc-editor.org/info/rfc2327>. <http://www.rfc-editor.org/info/rfc2327>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms "Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
 End of changes. 16 change blocks. 
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