[AVT] Potential overhead issues for RTP over DCCP
Damon Lanphear <damonlan@real.com> Wed, 19 June 2002 16:26 UTC
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Date: Wed, 19 Jun 2002 09:24:49 -0700
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Subject: [AVT] Potential overhead issues for RTP over DCCP
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All, At present there is some discussion on the Datagram Conegestion Control Protocol mailing list (DCCP, also known as DCP, see references below) with regards to the use of DCCP as an underlying transport for RTP. A central concern is that although one of the objectives of DCCP is to insure minimal overhead in terms of packet size and end node processing time, using RTP over DCCP will result in about 4 bytes of additional overhead per packet for redundant representation of a sequence number. This overhead is in addition to the potentially redundant information transmitted in RTCP RR's, which may be the same as that piggybacked on DCCP receiver reports. Redundant data in this case includes metrics for estimating the RTT, and a receiver loss metric. The tradeoff currently being considered is the 4 byte per packet overhead for a simplified API in which sequence numbers need not be represented to the application layer by DCCP on a per packet basis. In my opinion, the RTCP RR can be easily resolved when we assume that the problem domain of real-time metric reporting, and the use of these metrics by an RTP application is rather different that the use of reciever reports by DCCP. When this is taken into account, the consolidation of potentially redundant data in this case may not be appropriate. What are the group's thoughts on these issues? thanks, damon DCCP (DCP) references: http://www.icir.org/kohler/dcp/draft-floyd-dcp-problem-00b.txt http://www.icir.org/kohler/dcp/draft-kohler-dcp-03.txt http://www.icir.org/kohler/dcp/draft-padhye-dcp-ccid3-03.txt _______________________________________________ Audio/Video Transport Working Group avt@ietf.org https://www1.ietf.org/mailman/listinfo/avt
- [AVT] Potential overhead issues for RTP over DCCP Damon Lanphear