RTP Control Protocol (RTCP) Feedback for Congestion Control in Interactive Multimedia Conferences
draft-ietf-rmcat-rtp-cc-feedback-04

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 00
• 01
• 02
• 03
• 04

Network Working Group                                         C. Perkins
Internet-Draft                                     University of Glasgow
Intended status: Informational                              July 1, 2018
Expires: January 2, 2019

     RTP Control Protocol (RTCP) Feedback for Congestion Control in
                   Interactive Multimedia Conferences
                  draft-ietf-rmcat-rtp-cc-feedback-04

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 2, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Perkins                  Expires January 2, 2019                [Page 1]
Internet-Draft    RTCP Feedback for Congestion Control         July 2018

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

Perkins                  Expires January 2, 2019                [Page 2]
Internet-Draft    RTCP Feedback for Congestion Control         July 2018

   state of the network?  Traditional congestion control protocols, such
   as TCP, send acknowledgements with every packet (or, at least, every