The IESG has approved the following document:
- 'Coupled congestion control for RTP media'
  (draft-ietf-rmcat-coupled-cc-07.txt) as Experimental RFC

This document is the product of the RTP Media Congestion Avoidance Techniques
Working Group.

The IESG contact persons are Mirja Kühlewind and Spencer Dawkins.

A URL of this Internet Draft is:
https://datatracker.ietf.org/doc/draft-ietf-rmcat-coupled-cc/





Technical Summary

  The RMCAT working group is developing congestion control schemes for use
  with RTP. When multiple such congestion controlled RTP flows traverse the
  same network bottleneck, combining their controls can improve the total
  on-the-wire behavior in terms of delay, loss and fairness.  This document
  describes such a method for flows that have the same sender, in a way
  that is as flexible and simple as possible while minimizing the amount of
  changes needed to existing RTP applications. It specifies how to apply
  the method for the NADA congestion control algorithm, and provides
  suggestions on how to apply it to other congestion control algorithms.

Working Group Summary

  The draft has been under development in the working group for some years.
  Much of the time was taken waiting for the candidate congestion control
  algorithms to stabilise, mapping the algorithms to the mechanisms given
  in this draft, and deciding which congestion control algorithms should be
  supported. The coupled congestion control algorithm itself has proved
  reasonably stable. 
  
  The draft discusses how to apply coupled congestion control to NADA and
  Google Congestion Control. The mapping to NADA is in the main body of the
  draft, since NADA is nearing working group last call and believed stable.
  The mapping for Google Congestion Control is in an appendix, since Google
  Congestion Control is not yet finalised. There is no mapping for SCReAM
  at this time, but one could be added later if there was interest in doing
  so (nothing in SCReAM should prevent this). 

  Overall, the working group process has been relatively smooth, although
  not rapid. The main issue of contention was the choice of congestion
  control algorithm to which the mechanism should be applied - based on
  the maturity of the candidate congestion control algorithms, and the
  relative importance the authors of the candidates placed on coupled
  congestion control.

Document Quality

  The algorithm has been implemented in simulations and emulated testbeds.
  This is appropriate for an experimental protocol of this type, and meets
  the usual community evaluation standards for transport protocol research. 
  The draft has been reviewed by some authors of each candidate congestion
  control algorithm, with Xiaoqing Zhu and Stefan Holmer providing detailed 
  reviews and advice on integration with the congestion control proposals. 
  The draft is well written, and the mechanism is clearly specified. 

  There is no need for MIB Doctor, Media Type, or other expert review,
  since the proposed mechanism relies only on common RTP features and
  parameters that can be directly measured by the end-point using the
  mechanism.

Personnel

  The document shepherd is Colin Perkins.
  The responsible AS is Mirja Kühlewind.