draft-ietf-mmusic-rfc4566bis-22.txt   draft-ietf-mmusic-rfc4566bis-23.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 Intended status: Standards Track
Expires: January 1, 2018 C. Perkins Expires: March 20, 2018 C. Perkins
University of Glasgow University of Glasgow
A. Begen A. Begen
Networked Media Networked Media
June 30, 2017 September 16, 2017
SDP: Session Description Protocol SDP: Session Description Protocol
draft-ietf-mmusic-rfc4566bis-22 draft-ietf-mmusic-rfc4566bis-23
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
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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
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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 January 1, 2018. This Internet-Draft will expire on March 20, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 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.
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This document may contain material from IETF Documents or IETF This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this 10, 2008. The person(s) controlling the copyright in some of this
skipping to change at page 2, line 49 skipping to change at page 2, line 49
5.3. Session Name ("s=") . . . . . . . . . . . . . . . . . . . 13 5.3. Session Name ("s=") . . . . . . . . . . . . . . . . . . . 13
5.4. Session Information ("i=") . . . . . . . . . . . . . . . 13 5.4. Session Information ("i=") . . . . . . . . . . . . . . . 13
5.5. URI ("u=") . . . . . . . . . . . . . . . . . . . . . . . 14 5.5. URI ("u=") . . . . . . . . . . . . . . . . . . . . . . . 14
5.6. Email Address and Phone Number ("e=" and "p=") . . . . . 14 5.6. Email Address and Phone Number ("e=" and "p=") . . . . . 14
5.7. Connection Data ("c=") . . . . . . . . . . . . . . . . . 15 5.7. Connection Data ("c=") . . . . . . . . . . . . . . . . . 15
5.8. Bandwidth ("b=") . . . . . . . . . . . . . . . . . . . . 17 5.8. Bandwidth ("b=") . . . . . . . . . . . . . . . . . . . . 17
5.9. Timing ("t=") . . . . . . . . . . . . . . . . . . . . . . 18 5.9. Timing ("t=") . . . . . . . . . . . . . . . . . . . . . . 18
5.10. Repeat Times ("r=") . . . . . . . . . . . . . . . . . . . 19 5.10. Repeat Times ("r=") . . . . . . . . . . . . . . . . . . . 19
5.11. Time Zones ("z=") . . . . . . . . . . . . . . . . . . . . 19 5.11. Time Zones ("z=") . . . . . . . . . . . . . . . . . . . . 19
5.12. Encryption Keys ("k=") . . . . . . . . . . . . . . . . . 20 5.12. Encryption Keys ("k=") . . . . . . . . . . . . . . . . . 20
5.13. Attributes ("a=") . . . . . . . . . . . . . . . . . . . . 22 5.13. Attributes ("a=") . . . . . . . . . . . . . . . . . . . . 20
5.14. Media Descriptions ("m=") . . . . . . . . . . . . . . . . 23 5.14. Media Descriptions ("m=") . . . . . . . . . . . . . . . . 21
6. SDP Attributes . . . . . . . . . . . . . . . . . . . . . . . 25 6. SDP Attributes . . . . . . . . . . . . . . . . . . . . . . . 24
6.1. cat (category) . . . . . . . . . . . . . . . . . . . . . 26 6.1. cat (category) . . . . . . . . . . . . . . . . . . . . . 24
6.2. keywds (keywords) . . . . . . . . . . . . . . . . . . . . 26 6.2. keywds (keywords) . . . . . . . . . . . . . . . . . . . . 25
6.3. tool . . . . . . . . . . . . . . . . . . . . . . . . . . 27 6.3. tool . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.4. ptime (packet time) . . . . . . . . . . . . . . . . . . . 27 6.4. ptime (packet time) . . . . . . . . . . . . . . . . . . . 26
6.5. maxptime (maximum packet time) . . . . . . . . . . . . . 28 6.5. maxptime (maximum packet time) . . . . . . . . . . . . . 26
6.6. rtpmap . . . . . . . . . . . . . . . . . . . . . . . . . 28 6.6. rtpmap . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.7. Media Direction Attributes . . . . . . . . . . . . . . . 30 6.7. Media Direction Attributes . . . . . . . . . . . . . . . 29
6.7.1. recvonly (receive-only) . . . . . . . . . . . . . . . 31 6.7.1. recvonly (receive-only) . . . . . . . . . . . . . . . 29
6.7.2. sendrecv (send-receive) . . . . . . . . . . . . . . . 31 6.7.2. sendrecv (send-receive) . . . . . . . . . . . . . . . 30
6.7.3. sendonly (send-only) . . . . . . . . . . . . . . . . 32 6.7.3. sendonly (send-only) . . . . . . . . . . . . . . . . 30
6.7.4. inactive . . . . . . . . . . . . . . . . . . . . . . 32 6.7.4. inactive . . . . . . . . . . . . . . . . . . . . . . 31
6.8. orient (orientation) . . . . . . . . . . . . . . . . . . 33 6.8. orient (orientation) . . . . . . . . . . . . . . . . . . 31
6.9. type (conference type) . . . . . . . . . . . . . . . . . 33 6.9. type (conference type) . . . . . . . . . . . . . . . . . 32
6.10. charset (character set) . . . . . . . . . . . . . . . . . 34 6.10. charset (character set) . . . . . . . . . . . . . . . . . 32
6.11. sdplang (SDP language) . . . . . . . . . . . . . . . . . 35 6.11. sdplang (SDP language) . . . . . . . . . . . . . . . . . 33
6.12. lang (language) . . . . . . . . . . . . . . . . . . . . . 36 6.12. lang (language) . . . . . . . . . . . . . . . . . . . . . 34
6.13. framerate (frame rate) . . . . . . . . . . . . . . . . . 37 6.13. framerate (frame rate) . . . . . . . . . . . . . . . . . 35
6.14. quality . . . . . . . . . . . . . . . . . . . . . . . . . 38 6.14. quality . . . . . . . . . . . . . . . . . . . . . . . . . 36
6.15. fmtp (format parameters) . . . . . . . . . . . . . . . . 38 6.15. fmtp (format parameters) . . . . . . . . . . . . . . . . 36
7. Security Considerations . . . . . . . . . . . . . . . . . . . 39 7. Security Considerations . . . . . . . . . . . . . . . . . . . 37
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
8.1. The "application/sdp" Media Type . . . . . . . . . . . . 41 8.1. The "application/sdp" Media Type . . . . . . . . . . . . 39
8.2. Registration of Parameters . . . . . . . . . . . . . . . 43 8.2. Registration of Parameters . . . . . . . . . . . . . . . 41
8.2.1. Media Types ("media") . . . . . . . . . . . . . . . . 43 8.2.1. Media Types ("media") . . . . . . . . . . . . . . . . 41
8.2.2. Transport Protocols ("proto") . . . . . . . . . . . . 43 8.2.2. Transport Protocols ("proto") . . . . . . . . . . . . 41
8.2.3. Media Formats ("fmt") . . . . . . . . . . . . . . . . 44 8.2.3. Media Formats ("fmt") . . . . . . . . . . . . . . . . 42
8.2.4. Attribute Names ("att-field") . . . . . . . . . . . . 44 8.2.4. Attribute Names ("att-field") . . . . . . . . . . . . 42
8.2.5. Bandwidth Specifiers ("bwtype") . . . . . . . . . . . 47 8.2.5. Bandwidth Specifiers ("bwtype") . . . . . . . . . . . 45
8.2.6. Network Types ("nettype") . . . . . . . . . . . . . . 47 8.2.6. Network Types ("nettype") . . . . . . . . . . . . . . 45
8.2.7. Address Types ("addrtype") . . . . . . . . . . . . . 48 8.2.7. Address Types ("addrtype") . . . . . . . . . . . . . 46
8.2.8. Registration Procedure . . . . . . . . . . . . . . . 48 8.2.8. Registration Procedure . . . . . . . . . . . . . . . 46
8.3. Encryption Key Access Methods . . . . . . . . . . . . . . 49 8.3. Encryption Key Access Methods . . . . . . . . . . . . . . 47
8.4. Reorganization of the nettype Registry . . . . . . . . . 49 8.4. Reorganization of the nettype Registry . . . . . . . . . 47
8.5. Reorganization of the att-field Registries . . . . . . . 49 8.5. Reorganization of the att-field Registries . . . . . . . 47
9. SDP Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 50 9. SDP Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 48
10. Summary of Changes from RFC 4566 . . . . . . . . . . . . . . 55 10. Summary of Changes from RFC 4566 . . . . . . . . . . . . . . 53
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 56 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 54
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 56 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 54
12.1. Normative References . . . . . . . . . . . . . . . . . . 56 12.1. Normative References . . . . . . . . . . . . . . . . . . 54
12.2. Informative References . . . . . . . . . . . . . . . . . 57 12.2. Informative References . . . . . . . . . . . . . . . . . 55
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 60 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 58
1. Introduction 1. Introduction
When initiating multimedia teleconferences, voice-over-IP calls, When initiating multimedia teleconferences, voice-over-IP calls,
streaming video, or other sessions, there is a requirement to convey streaming video, or other sessions, there is a requirement to convey
media details, transport addresses, and other session description media details, transport addresses, and other session description
metadata to the participants. metadata to the participants.
SDP provides a standard representation for such information, SDP provides a standard representation for such information,
irrespective of how that information is transported. SDP is purely a irrespective of how that information is transported. SDP is purely a
skipping to change at page 20, line 37 skipping to change at page 20, line 37
If a session is likely to last several years, it is expected that the If a session is likely to last several years, it is expected that the
session description will be modified periodically rather than session description will be modified periodically rather than
transmit several years' worth of adjustments in one session transmit several years' worth of adjustments in one session
description. description.
5.12. Encryption Keys ("k=") 5.12. Encryption Keys ("k=")
k=<method> k=<method>
k=<method>:<encryption key> k=<method>:<encryption key>
If transported over a secure and trusted channel, the Session The "k=" line is obsolete and MUST NOT be used. It is included in
Description Protocol MAY be used to convey encryption keys. A simple this document for legacy reasons. One MUST NOT include a "k=" line
mechanism for key exchange is provided by the key line ("k="), in an SDP, and MUST discard it if it is received in an SDP.
although this is primarily supported for compatibility with older
implementations and its use is NOT RECOMMENDED. Work is in progress
to define new key exchange mechanisms for use with SDP [RFC4567]
[RFC4568], and it is expected that new applications will use those
mechanisms.
A key line is permitted before the first media entry (in which case
it applies to all media in the session), or for each media entry as
required. The format of keys and their usage are outside the scope
of this document, and the key field provides no way to indicate the
encryption algorithm to be used, key type, or other information about
the key: this is assumed to be provided by the higher-level protocol
using SDP. If there is a need to convey this information within SDP,
the extensions mentioned previously SHOULD be used. Many security
protocols require two keys: one for confidentiality, another for
integrity. This specification does not support transfer of two keys.
The method indicates the mechanism to be used to obtain a usable key
by external means, or from the encoded encryption key given. The
following methods are defined:
k=clear:<encryption key>
The encryption key is included untransformed in this key line.
This method MUST NOT be used unless it can be guaranteed that
the SDP is conveyed over a secure channel. The encryption key
is interpreted as text according to the charset attribute; use
the "k=base64:" method to convey characters that are otherwise
prohibited in SDP.
k=base64:<encoded encryption key>
The encryption key is included in this key line but has been
base64 encoded [RFC4648] because it includes characters that
are prohibited in SDP. This method MUST NOT be used unless it
can be guaranteed that the SDP is conveyed over a secure
channel.
k=uri:<URI to obtain key>
A Uniform Resource Identifier is included in the key line. The
URI refers to the data containing the key, and may require
additional authentication before the key can be returned. When
a request is made to the given URI, the reply should specify
the encoding for the key. The URI is often an Secure Socket
Layer/Transport Layer Security (SSL/TLS)-protected HTTP URI
("https:"), although this is not required.
k=prompt
No key is included in this SDP description, but the session or
media stream referred to by this key line is encrypted. The
user should be prompted for the key when attempting to join the
session, and this user-supplied key should then be used to
decrypt the media streams. The use of user-specified keys is
NOT RECOMMENDED, since such keys tend to have weak security
properties.
The key line MUST NOT be used unless it can be guaranteed that the
SDP is conveyed over a secure and trusted channel. An example of
such a channel might be SDP embedded inside an S/MIME message or a
TLS-protected HTTP session. It is important to ensure that the
secure channel is with the party that is authorised to join the
session, not an intermediary: if a caching proxy server is used, it
is important to ensure that the proxy is either trusted or unable to
access the SDP.
5.13. Attributes ("a=") 5.13. Attributes ("a=")
a=<attribute> a=<attribute>
a=<attribute>:<value> a=<attribute>:<value>
Attributes are the primary means for extending SDP. Attributes may Attributes are the primary means for extending SDP. Attributes may
be defined to be used as "session-level" attributes, "media-level" be defined to be used as "session-level" attributes, "media-level"
attributes, or both. attributes, or both.
skipping to change at page 56, line 24 skipping to change at page 54, line 24
(MMUSIC) working group have made comments and suggestions (MMUSIC) working group have made comments and suggestions
contributing to this document. contributing to this document.
12. References 12. References
12.1. Normative References 12.1. Normative References
[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-12 (work in draft-ietf-mmusic-data-channel-sdpneg-13 (work in
progress), March 2017. progress), September 2017.
[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-16 Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16
(work in progress), December 2016. (work in progress), December 2016.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>. <https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>. November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2978] Freed, N. and J. Postel, "IANA Charset Registration [RFC2978] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978, Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978,
October 2000, <http://www.rfc-editor.org/info/rfc2978>. October 2000, <https://www.rfc-editor.org/info/rfc2978>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <http://www.rfc-editor.org/info/rfc3629>. 2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, DOI 10.17487/RFC4566, Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
July 2006, <http://www.rfc-editor.org/info/rfc4566>. July 2006, <https://www.rfc-editor.org/info/rfc4566>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<http://www.rfc-editor.org/info/rfc4648>. <https://www.rfc-editor.org/info/rfc4648>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <https://www.rfc-editor.org/info/rfc5226>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
[RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific
Media Attributes in the Session Description Protocol Media Attributes in the Session Description Protocol
(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>. <https://www.rfc-editor.org/info/rfc5576>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying [RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <http://www.rfc-editor.org/info/rfc5646>. September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC5890] Klensin, J., "Internationalized Domain Names for [RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework", Applications (IDNA): Definitions and Document Framework",
RFC 5890, DOI 10.17487/RFC5890, August 2010, RFC 5890, DOI 10.17487/RFC5890, August 2010,
<http://www.rfc-editor.org/info/rfc5890>. <https://www.rfc-editor.org/info/rfc5890>.
12.2. Informative References 12.2. Informative References
[ITU.H332.1998] [ITU.H332.1998]
International Telecommunication Union, "H.323 extended for International Telecommunication Union, "H.323 extended for
loosely coupled conferences", ITU Recommendation H.332, loosely coupled conferences", ITU Recommendation H.332,
September 1998. September 1998.
[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>. <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
Announcement Protocol", RFC 2974, DOI 10.17487/RFC2974, Announcement Protocol", RFC 2974, DOI 10.17487/RFC2974,
October 2000, <http://www.rfc-editor.org/info/rfc2974>. October 2000, <https://www.rfc-editor.org/info/rfc2974>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<http://www.rfc-editor.org/info/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551, Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003, DOI 10.17487/RFC3551, July 2003,
<http://www.rfc-editor.org/info/rfc3551>. <https://www.rfc-editor.org/info/rfc3551>.
[RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth
Modifiers for RTP Control Protocol (RTCP) Bandwidth", Modifiers for RTP Control Protocol (RTCP) Bandwidth",
RFC 3556, DOI 10.17487/RFC3556, July 2003, RFC 3556, DOI 10.17487/RFC3556, July 2003,
<http://www.rfc-editor.org/info/rfc3556>. <https://www.rfc-editor.org/info/rfc3556>.
[RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute
in Session Description Protocol (SDP)", RFC 3605, in Session Description Protocol (SDP)", RFC 3605,
DOI 10.17487/RFC3605, October 2003, DOI 10.17487/RFC3605, October 2003,
<http://www.rfc-editor.org/info/rfc3605>. <https://www.rfc-editor.org/info/rfc3605>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<http://www.rfc-editor.org/info/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, [RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
"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,
<http://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,
<http://www.rfc-editor.org/info/rfc3890>. <https://www.rfc-editor.org/info/rfc3890>.
[RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E.
Carrara, "Key Management Extensions for Session Carrara, "Key Management Extensions for Session
Description Protocol (SDP) and Real Time Streaming Description Protocol (SDP) and Real Time Streaming
Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July
2006, <http://www.rfc-editor.org/info/rfc4567>. 2006, <https://www.rfc-editor.org/info/rfc4567>.
[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,
<http://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,
<http://www.rfc-editor.org/info/rfc4855>. <https://www.rfc-editor.org/info/rfc4855>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT) (ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245, Traversal for Offer/Answer Protocols", RFC 5245,
DOI 10.17487/RFC5245, April 2010, DOI 10.17487/RFC5245, April 2010,
<http://www.rfc-editor.org/info/rfc5245>. <https://www.rfc-editor.org/info/rfc5245>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008, DOI 10.17487/RFC5322, October 2008,
<http://www.rfc-editor.org/info/rfc5322>. <https://www.rfc-editor.org/info/rfc5322>.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, Protocol (SDP) Grouping Framework", RFC 5888,
DOI 10.17487/RFC5888, June 2010, DOI 10.17487/RFC5888, June 2010,
<http://www.rfc-editor.org/info/rfc5888>. <https://www.rfc-editor.org/info/rfc5888>.
[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,
<http://www.rfc-editor.org/info/rfc5905>. <https://www.rfc-editor.org/info/rfc5905>.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach, [RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity "TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544, Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544,
March 2012, <http://www.rfc-editor.org/info/rfc6544>. March 2012, <https://www.rfc-editor.org/info/rfc6544>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>. <https://www.rfc-editor.org/info/rfc6838>.
[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF", [RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
RFC 7405, DOI 10.17487/RFC7405, December 2014, RFC 7405, DOI 10.17487/RFC7405, December 2014,
<http://www.rfc-editor.org/info/rfc7405>. <https://www.rfc-editor.org/info/rfc7405>.
[RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and [RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
for Real-Time Transport Protocol (RTP) Sources", RFC 7656, for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
DOI 10.17487/RFC7656, November 2015, DOI 10.17487/RFC7656, November 2015,
<http://www.rfc-editor.org/info/rfc7656>. <https://www.rfc-editor.org/info/rfc7656>.
[RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M., [RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, Ed., "Real-Time Streaming Protocol and M. Stiemerling, Ed., "Real-Time Streaming Protocol
Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
2016, <http://www.rfc-editor.org/info/rfc7826>. 2016, <https://www.rfc-editor.org/info/rfc7826>.
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
EMail: M.Handley@cs.ucl.ac.uk EMail: M.Handley@cs.ucl.ac.uk
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