RTP Control Protocol (RTCP) Feedback for Congestion Control in Interactive Multimedia Conferences
draft-ietf-rmcat-rtp-cc-feedback-03

Document Type Active Internet-Draft (rmcat WG)
Last updated 2016-11-13
Replaces draft-perkins-rmcat-rtp-cc-feedback
Stream IETF
Intended RFC status Informational
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Stream WG state WG Document Aug 2014
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Network Working Group                                         C. Perkins
Internet-Draft                                     University of Glasgow
Intended status: Informational                         November 14, 2016
Expires: May 18, 2017

     RTP Control Protocol (RTCP) Feedback for Congestion Control in
                   Interactive Multimedia Conferences
                  draft-ietf-rmcat-rtp-cc-feedback-03

Abstract

   This memo discusses the types of congestion control feedback that it
   is possible to send using the RTP Control Protocol (RTCP), and their
   suitability of use in implementing congestion control for unicast
   multimedia applications.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 18, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Internet-Draft    RTCP Feedback for Congestion Control     November 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Possible Models for RTCP Feedback . . . . . . . . . . . . . .   2
   3.  What Feedback is Achievable With RTCP?  . . . . . . . . . . .   4
     3.1.  Scenario 1: Voice Telephony . . . . . . . . . . . . . . .   4
     3.2.  Scenario 2: Point-to-Point Video Conference . . . . . . .   6
     3.3.  Scenario 3: Group Video Conference  . . . . . . . . . . .  10
     3.4.  Scenario 4: Screen Sharing  . . . . . . . . . . . . . . .  10
   4.  Discussion and Conclusions  . . . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   The coming deployment of WebRTC systems raises the prospect that high
   quality video conferencing will see extremely wide use.  To ensure
   the stability of the network in the face of this use, WebRTC systems
   will need to use some form of congestion control for their RTP-based
   media traffic.  To develop such congestion control, it is necessary
   to understand the sort of congestion feedback that can be provided
   within the framework of RTP [RFC3550] and the RTP Control Protocol
   (RTCP).  It then becomes possible to determine if this is sufficient
   for congestion control, or if some form of RTP extension is needed.

   This memo considers the congestion feedback that can be sent using
   RTCP under the RTP/SAVPF profile [RFC5124] (the secure version of the
   RTP/AVPF profile [RFC4585]).  This profile was chosen as it forms the
   basis for media transport in WebRTC [I-D.ietf-rtcweb-rtp-usage]
   systems.  Nothing in this memo is specific to the secure version of
   the profile, or to WebRTC, however.

2.  Possible Models for RTCP Feedback

   Several questions need to be answered when providing RTCP reception
   quality feedback for congestion control purposes.  These include:

   o  How often is feedback needed?

   o  How much overhead is acceptable?

   o  How much, and what, data does each report contain?

   The key question is how often does the receiver need to send feedback
   on the reception quality it is experiencing, and hence the congestion

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