draft-ietf-mmusic-rfc4566bis-06.txt   draft-ietf-mmusic-rfc4566bis-07.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: February 26, 2013 C. Perkins Expires: August 29, 2013 C. Perkins
University of Glasgow University of Glasgow
A. Begen A. Begen
Cisco Cisco
August 25, 2012 February 25, 2013
SDP: Session Description Protocol SDP: Session Description Protocol
draft-ietf-mmusic-rfc4566bis-06 draft-ietf-mmusic-rfc4566bis-07
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
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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 February 26, 2013. This Internet-Draft will expire on August 29, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 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
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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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o If the session is multicast, the connection address will be an IP o If the session is multicast, the connection address will be an IP
multicast group address. If the session is not multicast, then multicast group address. If the session is not multicast, then
the connection address contains the unicast IP address of the the connection address contains the unicast IP address of the
expected data source or data relay or data sink as determined by expected data source or data relay or data sink as determined by
additional attribute fields. It is not expected that unicast additional attribute fields. It is not expected that unicast
addresses will be given in a session description that is addresses will be given in a session description that is
communicated by a multicast announcement, though this is not communicated by a multicast announcement, though this is not
prohibited. prohibited.
o Sessions using an IPv4 multicast connection address MUST also have o Sessions using an IP4 multicast connection address MUST also have
a time to live (TTL) value present in addition to the multicast a time to live (TTL) value present in addition to the multicast
address. The TTL and the address together define the scope with address. The TTL and the address together define the scope with
which multicast packets sent in this session will be sent. TTL which multicast packets sent in this session will be sent. TTL
values MUST be in the range 0-255. Although the TTL MUST be values MUST be in the range 0-255. Although the TTL MUST be
specified, its use to scope multicast traffic is deprecated; specified, its use to scope multicast traffic is deprecated;
applications SHOULD use an administratively scoped address applications SHOULD use an administratively scoped address
instead. instead.
The TTL for the session is appended to the address using a slash as a The TTL for the session is appended to the address using a slash as a
separator. An example is: separator. An example is:
c=IN IP4 233.252.0.1/127 c=IN IP4 233.252.0.1/127
IPv6 multicast does not use TTL scoping, and hence the TTL value MUST IP6 multicast does not use TTL scoping, and hence the TTL value MUST
NOT be present for IPv6 multicast. It is expected that IPv6 scoped NOT be present for IP6 multicast. It is expected that IP6 scoped
addresses will be used to limit the scope of conferences. addresses will be used to limit the scope of conferences.
Hierarchical or layered encoding schemes are data streams where the Hierarchical or layered encoding schemes are data streams where the
encoding from a single media source is split into a number of layers. encoding from a single media source is split into a number of layers.
The receiver can choose the desired quality (and hence bandwidth) by The receiver can choose the desired quality (and hence bandwidth) by
only subscribing to a subset of these layers. Such layered encodings only subscribing to a subset of these layers. Such layered encodings
are normally transmitted in multiple multicast groups to allow are normally transmitted in multiple multicast groups to allow
multicast pruning. This technique keeps unwanted traffic from sites multicast pruning. This technique keeps unwanted traffic from sites
only requiring certain levels of the hierarchy. For applications only requiring certain levels of the hierarchy. For applications
requiring multiple multicast groups, we allow the following notation requiring multiple multicast groups, we allow the following notation
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c=IN IP4 233.252.0.1/127/3 c=IN IP4 233.252.0.1/127/3
would state that addresses 233.252.0.1, 233.252.0.2, and 233.252.0.3 would state that addresses 233.252.0.1, 233.252.0.2, and 233.252.0.3
are to be used at a TTL of 127. This is semantically identical to are to be used at a TTL of 127. This is semantically identical to
including multiple "c=" lines in a media description: including multiple "c=" lines in a media description:
c=IN IP4 233.252.0.1/127 c=IN IP4 233.252.0.1/127
c=IN IP4 233.252.0.2/127 c=IN IP4 233.252.0.2/127
c=IN IP4 233.252.0.3/127 c=IN IP4 233.252.0.3/127
Similarly, an IPv6 example would be: Similarly, an IP6 example would be:
c=IN IP6 FF15::101/3 c=IN IP6 FF15::101/3
which is semantically equivalent to: which is semantically equivalent to:
c=IN IP6 FF15::101 c=IN IP6 FF15::101
c=IN IP6 FF15::102 c=IN IP6 FF15::102
c=IN IP6 FF15::103 c=IN IP6 FF15::103
(remembering that the TTL field is not present in IPv6 multicast). (remembering that the TTL field is not present in IP6 multicast).
Multiple addresses or "c=" lines MAY be specified on a per-media Multiple addresses or "c=" lines MAY be specified on a per-media
basis only if they provide multicast addresses for different layers basis only if they provide multicast addresses for different layers
in a hierarchical or layered encoding scheme. They MUST NOT be in a hierarchical or layered encoding scheme. They MUST NOT be
specified for a session-level "c=" field. specified for a session-level "c=" field.
The slash notation for multiple addresses described above MUST NOT be The slash notation for multiple addresses described above MUST NOT be
used for IP unicast addresses. used for IP unicast addresses.
5.8. Bandwidth ("b=") 5.8. Bandwidth ("b=")
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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 )
"/" ttl [ "/" integer ] "/" ttl [ "/" integer ]
; IPv4 multicast addresses may be in the ; IP4 multicast addresses may be in the
; range 224.0.0.0 to 239.255.255.255 ; range 224.0.0.0 to 239.255.255.255
m1 = ("22" ("4"/"5"/"6"/"7"/"8"/"9")) / m1 = ("22" ("4"/"5"/"6"/"7"/"8"/"9")) /
("23" DIGIT ) ("23" DIGIT )
IP6-multicast = IP6-address [ "/" integer ] IP6-multicast = IP6-address [ "/" integer ]
; IPv6 address starting with FF ; IP6 address starting with FF
ttl = (POS-DIGIT *2DIGIT) / "0" ttl = (POS-DIGIT *2DIGIT) / "0"
FQDN = 4*(alpha-numeric / "-" / ".") FQDN = 4*(alpha-numeric / "-" / ".")
; fully qualified domain name as specified ; fully qualified domain name as specified
; in RFC 1035 (and updates) ; in RFC 1035 (and updates)
IP4-address = b1 3("." decimal-uchar) IP4-address = b1 3("." decimal-uchar)
b1 = decimal-uchar b1 = decimal-uchar
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; ALPHA, DIGIT, CRLF, SP, VCHAR: from RFC 5234 ; ALPHA, DIGIT, CRLF, SP, VCHAR: from RFC 5234
; URI-reference: from RFC 3986 ; URI-reference: from RFC 3986
; addr-spec: from RFC 5322 ; addr-spec: from RFC 5322
10. Summary of Changes from RFC 4566 10. Summary of Changes from RFC 4566
The ABNF rule for IP6-address has been corrected. As a result, the The ABNF rule for IP6-address has been corrected. As a result, the
ABNF rule for IP6-multicast has changed, and the (now unused) rules ABNF rule for IP6-multicast has changed, and the (now unused) rules
for hexpart, hexseq, and hex4 have been removed. for hexpart, hexseq, and hex4 have been removed.
IPv4 unicast and multicast addresses in the example SDP descriptions IP4 unicast and multicast addresses in the example SDP descriptions
have been revised per RFCs 5735 and 5771. have been revised per RFCs 5735 and 5771.
Text in Section 5.2 has been revised to clarify the use of local Text in Section 5.2 has been revised to clarify the use of local
addresses in case of ICE-like SDP extensions. addresses in case of ICE-like SDP extensions.
Normative and informative references have been updated. Normative and informative references have been updated.
The following purely editorial changes have been made: The following purely editorial changes have been made:
o Section 4.6: fix typo in first sentence: "sets" -> "set" o Section 4.6: fix typo in first sentence: "sets" -> "set"
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o Section 5.10: fix typo: "To make description" -> "To make the o Section 5.10: fix typo: "To make description" -> "To make the
description" description"
o Section 5.11: use "session description" rather than "session o Section 5.11: use "session description" rather than "session
announcement" in the final paragraph announcement" in the final paragraph
o Section 7: fix typo: "distribute session description" -> o Section 7: fix typo: "distribute session description" ->
"distribute session descriptions" "distribute session descriptions"
Clarify the use of multiple "a=sdplang:" and "a=lang:" attributes, To-do: Clarify the use of multiple "a=sdplang:" and "a=lang:"
and when "a=sdplang:" should be used. attributes. In general, review the text proposed by Paul K. on 1/3/
2013 and incorporate into the text to clarify the usage of session-
level attributes. Consider including the case-sensitivity rules from
RFC 3555 in this document.
11. Acknowledgements 11. Acknowledgements
Many people in the IETF Multiparty Multimedia Session Control Many people in the IETF Multiparty Multimedia Session Control
(MMUSIC) working group have made comments and suggestions (MMUSIC) working group have made comments and suggestions
contributing to this document. In particular, we would like to thank contributing to this document. In particular, we would like to thank
Eve Schooler, Steve Casner, Bill Fenner, Allison Mankin, Ross Eve Schooler, Steve Casner, Bill Fenner, Allison Mankin, Ross
Finlayson, Peter Parnes, Joerg Ott, Carsten Bormann, Steve Hanna, Finlayson, Peter Parnes, Joerg Ott, Carsten Bormann, Steve Hanna,
Jonathan Lennox, Keith Drage, Sean Olson, Bernie Hoeneisen, Jonathan Jonathan Lennox, Keith Drage, Sean Olson, Bernie Hoeneisen, Jonathan
Rosenberg, John Elwell, Flemming Andreasen, Jon Peterson, Spencer Rosenberg, John Elwell, Flemming Andreasen, Jon Peterson, Spencer
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Streaming Protocol (RTSP)", RFC 4567, July 2006. Streaming Protocol (RTSP)", RFC 4567, July 2006.
[RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session
Description Protocol (SDP) Security Descriptions for Description Protocol (SDP) Security Descriptions for
Media Streams", RFC 4568, July 2006. Media Streams", RFC 4568, July 2006.
[RFC5322] Resnick, P., Ed., "Internet Message Format", [RFC5322] Resnick, P., Ed., "Internet Message Format",
RFC 5322, October 2008. RFC 5322, October 2008.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications
and Registration Procedures", BCP 13, RFC 4288, and Registration Procedures", RFC 4288,
December 2005. December 2005.
Authors' Addresses Authors' Addresses
Mark Handley Mark Handley
University College London University College London
Department of Computer Science Department of Computer Science
London WC1E 6BT London WC1E 6BT
UK UK
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