draft-ietf-avtcore-5761-update-05.txt   draft-ietf-avtcore-5761-update-06.txt 
Network Working Group C. Holmberg Network Working Group C. Holmberg
Internet-Draft Ericsson Internet-Draft Ericsson
Updates: 5761 (if approved) October 4, 2016 Updates: 5761 (if approved) October 13, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: April 7, 2017 Expires: April 16, 2017
RFC 5761 SDP Offer/Answer Clarifications RTP/RTCP Multiplexing SDP Offer/Answer Clarifications
draft-ietf-avtcore-5761-update-05.txt draft-ietf-avtcore-5761-update-06.txt
Abstract Abstract
This document updates RFC 5761 by clarifying the SDP offer/answer This document updates RFC 5761 by clarifying the SDP offer/answer
negotiation of RTP and RTCP multiplexing. It makes it clear that an negotiation of RTP and RTCP multiplexing. It makes it clear that an
answerer can only include an "a=rtcp-mux" attribute in an SDP answer answerer can only include an "a=rtcp-mux" attribute in an SDP answer
if the associated SDP offer contained the attribute. if the associated SDP offer contained the attribute.
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 April 7, 2017. This Internet-Draft will expire on April 16, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
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and RTCP to port 49170 on IPv6 address 2001:DB8::211:24ff:fea3:7a2e. and RTCP to port 49170 on IPv6 address 2001:DB8::211:24ff:fea3:7a2e.
If the offer contains the "a=rtcp-mux" attribute, and if the answerer If the offer contains the "a=rtcp-mux" attribute, and if the answerer
wishes to multiplex RTP and RTCP onto a single port, it MUST include a wishes to multiplex RTP and RTCP onto a single port, it MUST include a
media-level "a=rtcp-mux" attribute in the answer. The RTP payload media-level "a=rtcp-mux" attribute in the answer. The RTP payload
types used in the answer MUST conform to the rules in Section 4. If types used in the answer MUST conform to the rules in Section 4. If
the offer does not contain the "a=rtcp-mux" attribute the answerer the offer does not contain the "a=rtcp-mux" attribute the answerer
MUST NOT include an "a=rtcp-mux" attribute in the answer, and the MUST NOT include an "a=rtcp-mux" attribute in the answer, and the
answerer MUST NOT multiplex RTP and RTCP packets on a single port. answerer MUST NOT multiplex RTP and RTCP packets on a single port.
If the answerer includes an "a=rtcp-mux" attribute in the answer, the If the answer contains an "a=rtcp-mux" attribute, the offerer and
offerer and answerer MUST multiplex RTP and RTCP packets on a single answerer MUST multiplex RTP and RTCP packets on a single port.
port.
If the answer does not contain an "a=rtcp-mux" attribute, the offerer If the answer does not contain an "a=rtcp-mux" attribute, the offerer
and answerer MUST NOT multiplex RTP and RTCP packets on a single port. and answerer MUST NOT multiplex RTP and RTCP packets on a single port.
Instead, they should send and receive RTCP on a port allocated Instead, they should send and receive RTCP on a port allocated
according to the usual port-selection rules (either the port pair, or according to the usual port-selection rules (either the port pair, or
a signalled port if the "a=rtcp:" attribute [10] is also included). a signalled port if the "a=rtcp:" attribute [10] is also included).
This will occur when talking to a peer that does not understand the This will occur when talking to a peer that does not understand the
"a=rtcp-mux" attribute. "a=rtcp-mux" attribute.
When SDP is used in a declarative manner, the presence of an "a=rtcp- When SDP is used in a declarative manner, the presence of an "a=rtcp-
mux" attribute signals that the sender will multiplex RTP and RTCP on mux" attribute signals that the sender will multiplex RTP and RTCP on
the same port. The receiver MUST be prepared to receive RTCP packets the same port. The receiver MUST be prepared to receive RTCP packets
on the RTP port, and any resource reservation needs to be made on the RTP port, and any resource reservation needs to be made
including the RTCP bandwidth. including the RTCP bandwidth.
4. Security Considerations 4. Security Considerations
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5. IANA Considerations 5. IANA Considerations
IANA is requested to add a reference to this document for the add- IANA is requested to add a reference to this document for the add-
field (media level only) registration "rtcp-mux" in Session field (media level only) registration "rtcp-mux" in Session
Description Protocol (SDP) Parameters registry. Description Protocol (SDP) Parameters registry.
6. Acknowledgements 6. Acknowledgements
Thanks to Colin Perkins, Magnus Westerlund, Paul Kyzivat, Roni Even Thanks to Colin Perkins, Magnus Westerlund, Paul Kyzivat, Roni Even
for providing comments on the document. Thomas Belling provided for providing comments on the document. Thomas Belling provided
useful input in the discussions that took place in 3GPP and resulated useful input in the discussions that took place in 3GPP and resulted
in the submission of the document. Elwyn Davies performed the Gen- in the submission of the document. Elwyn Davies performed the Gen-
ART review. ART review. Rick Casarez performed the Ops-Dir review. Alissa
Cooper and Spencer Dawkins provided IESG review comments.
7. Change Log 7. Change Log
[RFC EDITOR NOTE: Please remove this section when publishing] [RFC EDITOR NOTE: Please remove this section when publishing]
Change from -05
o Changes based on IESG- and Gen-Art reviews:
o - Change of document title.
o - Editorial fix.
Change from -04 Change from -04
o Change of document title. o Change of document title.
Change from -03 Change from -03
o Addition to IANA Considerations. o Addition to IANA Considerations.
Change from -02 Change from -02
o Editorial change based on Gen-ART review of Elwyn Davis o Editorial change based on Gen-ART review of Elwyn Davis
(https://www.ietf.org/mail-archive/web/gen-art/current/ (https://www.ietf.org/mail-archive/web/gen-art/current/
msg13713.html). msg13713.html).
Change from -01 Change from -01
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