Differentiated Services (DiffServ) and Real-time Communication
draft-ietf-dart-dscp-rtp-09

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Last updated 2014-11-09
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DiffServ Applied to Real-time Transports                   D. Black, Ed.
Internet-Draft                                                       EMC
Intended status: Informational                                  P. Jones
Expires: May 13, 2015                                              Cisco
                                                        November 9, 2014

     Differentiated Services (DiffServ) and Real-time Communication
                      draft-ietf-dart-dscp-rtp-09

Abstract

   This memo describes the interaction between Differentiated Services
   (DiffServ) network quality of service (QoS) functionality and real-
   time network communication, including communication based on the
   Real-time Transport Protocol (RTP).  DiffServ is based on network
   nodes applying different forwarding treatments to packets whose IP
   headers are marked with different DiffServ Code Points (DSCPs).
   WebRTC applications, as well as some conferencing applications, have
   begun using the Session Description Protocol (SDP) bundle negotiation
   mechanism to send multiple traffic streams with different QoS
   requirements using the same network 5-tuple.  The results of using
   multiple DSCPs to obtain different QoS treatments within a single
   network 5-tuple (e.g., reordering) have transport protocol
   interactions, particularly with congestion control functionality.  In
   addition, DSCP markings may be changed or removed between the traffic
   source and destination.  This memo covers the implications of these
   DiffServ aspects for real-time network communication, including
   WebRTC.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 13, 2015.

Black & Jones             Expires May 13, 2015                  [Page 1]
Internet-Draft        DiffServ and RT Communication        November 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
   Provisions Relating to IETF Documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Real Time Communications  . . . . . . . . . . . . . . . . . .   3
     2.1.  RTP Background  . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  RTP Multiplexing  . . . . . . . . . . . . . . . . . . . .   6
   3.   Differentiated Services (DiffServ) . . . . . . . . . . . . .   7
     3.1.  Diffserv PHBs (Per-Hop Behaviors) . . . . . . . . . . . .   9
     3.2.  Traffic Classifiers and DSCP Remarking  . . . . . . . . .  10
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   5.  DiffServ Interactions . . . . . . . . . . . . . . . . . . . .  12
     5.1.  DiffServ, Reordering and Transport Protocols  . . . . . .  13
     5.2.  DiffServ, Reordering and Real-Time Communication  . . . .  15
     5.3.  Drop Precedence and Transport Protocols . . . . . . . . .  16
     5.4.  DiffServ and RTCP . . . . . . . . . . . . . . . . . . . .  17
   6.  Guidelines  . . . . . . . . . . . . . . . . . . . . . . . . .  17
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  20
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  20
     10.2.  Informative References . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   This memo describes the interactions between Differentiated Services
   (DiffServ) network quality of service (QoS) functionality [RFC2475]
   and real-time network communication, including communication based on
   the Real-time Transport Protocol (RTP) [RFC3550].  DiffServ is based
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