On the Suitability of RTCP for Congestion Control Feedback
I submitted a draft on the use of RTCP Feedback for Unicast Multimedia Congestion Control. Congestion control requires a feedback loop, to report on reception quality, and in the case of RTP-based multimedia, this is has typically been provided by RTCP feedback. There have been some suggestions in the working group that RTCP feedback is too slow for effective congestion control. This draft provides a rough sketch of how quickly feedback can be provided by RTCP. It seems clear that per-packet feedback cannot be provided using RTCP, but per-frame feedback is very possible. If RTCP is to be used in it's current form for congestion feedback, then the algorithms should be designed to work with feedback per-frame or per-RTT, rather than per packet.
Slides from my talk at IETF 86 are available.