Coupled congestion control for RTP media
draft-welzl-rmcat-coupled-cc-01

The information below is for an old version of the document
Document Type Active Internet-Draft (individual)
Last updated 2013-06-14
Replaced by draft-ietf-rmcat-coupled-cc
Stream (None)
Intended RFC status (None)
Formats pdf htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
RTP Media Congestion Avoidance                                  M. Welzl
Techniques (rmcat)                                              S. Islam
Internet-Draft                                               S. Gjessing
Intended status: Experimental                         University of Oslo
Expires: December 16, 2013                                 June 14, 2013

                Coupled congestion control for RTP media
                    draft-welzl-rmcat-coupled-cc-01

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
   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 December 16, 2013.

Copyright Notice

   Copyright (c) 2013 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

Welzl, et al.           Expires December 16, 2013               [Page 1]
Internet-Draft  Coupled congestion control for RTP media       June 2013

   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  . . . . . . . . . . . . . . . . . .  7
       5.3.2.  Example operation  . . . . . . . . . . . . . . . . . . 10
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 15
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 15
   Appendix A.  Changes from -00 to -01 . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15

Welzl, et al.           Expires December 16, 2013               [Page 2]
Internet-Draft  Coupled congestion control for RTP media       June 2013

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
   rate to each RTP session.  This way, priorities could also be
   implemented quite easily, as a function of the scheduler; honoring
   user-specified priorities is, for example, required by rtcweb
   [rtcweb-usecases].

   The Congestion Manager (CM) [RFC3124] provides a single congestion
   controller with a scheduling function just as described above.  It is
Show full document text