draft-ietf-avtcore-ecn-for-rtp
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP, Internet Engineering Task Force, RFC 6679, August 2012. DOI:10.17487/RFC6679
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, May 2012, Work in progress (draft-ietf-avtcore-ecn-for-rtp-08.txt).
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This version is a minor update, to address IESG review comments. The most significant change is a fix to the qdtext ABNF, to properly allow quoted values, but there are some minor clarifications throughout.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, March 2012, Work in progress (draft-ietf-avtcore-ecn-for-rtp-07.txt).
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This version addresses review comments from the Area Director and the IANA. The changes in this version are:
- Clarify the name of the STUN attribute (ECN-CHECK) per IANA comments
- Remove reference to RTP no-op
- Fix Block Length in Section 5.2
- Clarify handling of counter wraps in Section 5.1
- Clarify "other reactions" in Section 7.3.3
- Make reference to RFC4566 normative
- Fix editorial nits
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, February 2012, Work in progress (draft-ietf-avtcore-ecn-for-rtp-06.txt).
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The main changes in this version are to add some discussion about the conservative nature of the rules for use of ECN with multicast groups, and to update the rules regarding timing of STUN connectivity checks. There are also a number of more minor editorial fixes. It's believed that this version addresses all the working group last call comments.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, October 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-05.txt).
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This revision addresses many of the working group last call comments. These were mostly minor clarifications and editorial corrections, but there were some significant issues raised:
- When using STUN to determine is ECN is supported on the path, as part of an ICE exchange, the additional checks for ECN support happen after the regular ICE exchange, but before media flows. This is problematic if the call has been accepted, since it can cause media clipping. It is proposed to allow the media to start without using ECN, with the STUN checks to running in parallel (at a low rate), and then switching to using ECN if they succeed, to improve the user experience.
- When using ECN-marked STUN packets to determine if ECN is supported on the path, the STUN checks may be lost. This could be due to congestion on the path, or because of a middlebox that is not ECN capable, and discards ECN-marked packets. Since the aim is to detect such middleboxes, lost ECN-marked STUN requests should be retransmitted up to four times, to give confidence that the loss is not just due to congestion.
- Support for multicast RTP sessions using ECN, to clarify that when ECN for RTP is used with SSM groups using unicast feedback, ECN reports will go to the feedback target, which must then send them to the original media source.
- It was noted that multicast sessions will only use ECN if every receiver, and the path to each, supports ECN. This is an obvious scalability problem for large multicast groups. The alternative, allowing groups where some receivers support ECN and some don't, has serious fairness issues, which we haven't yet solved. We propose to document this issue, and note that the current, very conservative, rules may be relaxed in a future version of the specification, but not to address this issue in the first version of the standard.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, July 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-04.txt).
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Fix typos.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, July 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-03.txt).
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Assorted minor clarifications and editorial fixes throughout.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, May 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-02.txt).
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Magnus Westerlund summarised the changes in this version in a post to the AVTCORE mailing list.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, March 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-01.txt).
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Clarify terminology. Clarify timeout behaviour. Clarify behaviour of ECN with multicast RTP sessions. Allow the SDP "a=ecn-capable-rtp" attribute at session level. Allow random choice of ECT value. Clarify behaviour of the ICE option tag. Expand discussion of the appropriate response to congestion notifications.
- Magnus Westerlund, Ingemar Johansson, Colin Perkins, Piers O'Hanlon, and Ken Carlberg, Explicit Congestion Notification (ECN) for RTP over UDP (.txt|.pdf), Internet Engineering Task Force, January 2011, Work in progress (draft-ietf-avtcore-ecn-for-rtp-00.txt).
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Add Section 3.3 on Interoperability. Clarify what SSRCs are included in ECN Summary Report packets. Clarify behaviour with IP multicast. Add ABNF for new SDP parameters, and clarify signalling behaviour, and add SDP examples. Add Section 7.1 on Negotiation of ECN Capability. Update IANA Considerations. Assorted minor clarifications and editorial fixes.
This draft replaces draft-ietf-avt-ecn-for-rtp