Coupled congestion control for RTP media
draft-welzl-rmcat-coupled-cc-03

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RTP Media Congestion Avoidance                                  M. Welzl
Techniques (rmcat)                                              S. Islam
Internet-Draft                                               S. Gjessing
Intended status: Experimental                         University of Oslo
Expires: November 8, 2014                                    May 7, 2014

                Coupled congestion control for RTP media
                    draft-welzl-rmcat-coupled-cc-03

Abstract

   When multiple congestion controlled RTP sessions traverse the same
   network bottleneck, it can be beneficial to combine their controls
   such that the total on-the-wire behavior is improved.  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.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on November 8, 2014.

Copyright Notice

   Copyright (c) 2014 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Limitations  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Architectural overview . . . . . . . . . . . . . . . . . . . .  5
   5.  Roles  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.1.  SBD  . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.2.  FSE  . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.3.  Flows  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
       5.3.1.  Example algorithm 1 - Active FSE . . . . . . . . . . .  7
       5.3.2.  Example algorithm 2 - Conservative Active FSE  . . . .  8
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 11
   Appendix A.  Example algorithm - Passive FSE . . . . . . . . . . . 11
     A.1.  Example operation (passive)  . . . . . . . . . . . . . . . 14
   Appendix B.  Change log  . . . . . . . . . . . . . . . . . . . . . 18
     B.1.  Changes from -00 to -01  . . . . . . . . . . . . . . . . . 18
     B.2.  Changes from -01 to -02  . . . . . . . . . . . . . . . . . 18
     B.3.  Changes from -02 to -03  . . . . . . . . . . . . . . . . . 18
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18

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1.  Introduction

   When there is enough data to send, a congestion controller must
   increase its sending rate until the path's capacity has been reached;
   depending on the controller, sometimes the rate is increased further,
   until packets are ECN-marked or dropped.  This process inevitably
   creates undesirable queuing delay -- an effect that is amplified when
   multiple congestion controlled connections traverse the same network
   bottleneck.  When such connections originate from the same host, it
   would therefore be ideal to use only one single sender-side
   congestion controller which determines the overall allowed sending
   rate, and then use a local scheduler to assign a proportion of this
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