Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions
RFC 8083

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

• Versions
• 00
• 01
• 02
• 03
• 04
• 05
• 06
• 07
• 08
• 09
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18

Internet Engineering Task Force (IETF)                        C. Perkins
Request for Comments: 8083                         University of Glasgow
Updates: 3550                                                   V. Singh
Category: Standards Track                                   callstats.io
ISSN: 2070-1721                                               March 2017

Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions

Abstract

   The Real-time Transport Protocol (RTP) is widely used in telephony,
   video conferencing, and telepresence applications.  Such applications
   are often run on best-effort UDP/IP networks.  If congestion control
   is not implemented in these applications, then network congestion can
   lead to uncontrolled packet loss and a resulting deterioration of the
   user's multimedia experience.  The congestion control algorithm acts
   as a safety measure by stopping RTP flows from using excessive
   resources and protecting the network from overload.  At the time of
   this writing, however, while there are several proprietary solutions,
   there is no standard algorithm for congestion control of interactive
   RTP flows.

   This document does not propose a congestion control algorithm.  It
   instead defines a minimal set of RTP circuit breakers: conditions
   under which an RTP sender needs to stop transmitting media data to
   protect the network from excessive congestion.  It is expected that,
   in the absence of long-lived excessive congestion, RTP applications
   running on best-effort IP networks will be able to operate without
   triggering these circuit breakers.  To avoid triggering the RTP
   circuit breaker, any Standards Track congestion control algorithms
   defined for RTP will need to operate within the envelope set by these
   RTP circuit breaker algorithms.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8083.

Perkins & Singh              Standards Track                    [Page 1]
RFC 8083                  RTP Circuit Breakers                March 2017

Copyright Notice

   Copyright (c) 2017 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  RTP Circuit Breakers for Systems Using the RTP/AVP Profile  .   8
     4.1.  RTP/AVP Circuit Breaker #1: RTCP Timeout  . . . . . . . .  10
     4.2.  RTP/AVP Circuit Breaker #2: Media Timeout . . . . . . . .  11
     4.3.  RTP/AVP Circuit Breaker #3: Congestion  . . . . . . . . .  12
     4.4.  RTP/AVP Circuit Breaker #4: Media Usability . . . . . . .  16
     4.5.  Ceasing Transmission  . . . . . . . . . . . . . . . . . .  17
   5.  RTP Circuit Breakers and the RTP/AVPF and RTP/SAVPF Profiles   18
   6.  Impact of RTCP Extended Reports (XR)  . . . . . . . . . . . .  19
   7.  Impact of Explicit Congestion Notification (ECN)  . . . . . .  19
   8.  Impact of Bundled Media and Layered Coding  . . . . . . . . .  20
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  21
     10.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  25
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

Perkins & Singh              Standards Track                    [Page 2]
RFC 8083                  RTP Circuit Breakers                March 2017

1.  Introduction

   The Real-time Transport Protocol (RTP) [RFC3550] is widely used in
   voice-over-IP, video teleconferencing, and telepresence systems.