Multiple RTP Sessions on a Single Lower-Layer Transport
draft-westerlund-avtcore-transport-multiplexing-04

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Network Working Group                                      M. Westerlund
Internet-Draft                                                  Ericsson
Intended status: Standards Track                              C. Perkins
Expires: April 25, 2013                            University of Glasgow
                                                        October 22, 2012

        Multiple RTP Sessions on a Single Lower-Layer Transport
           draft-westerlund-avtcore-transport-multiplexing-04

Abstract

   This document specifies how multiple RTP sessions are to be
   multiplexed on the same lower-layer transport, e.g. a UDP flow.  It
   discusses various requirements that have been raised and their
   feasibility, which results in a solution with a certain
   applicability.  A solution is recommended and that solution is
   provided in more detail, including signalling and examples.

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   This Internet-Draft will expire on April 25, 2013.

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Westerlund & Perkins     Expires April 25, 2013                 [Page 1]
Internet-Draft  Multiple RTP Session on Single Transport    October 2012

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Requirements Language  . . . . . . . . . . . . . . . . . .  5
   3.  Motivations  . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  NAT and Firewalls  . . . . . . . . . . . . . . . . . . . .  5
     3.2.  No Transport Level QoS . . . . . . . . . . . . . . . . . .  5
     3.3.  Multiple RTP sessions  . . . . . . . . . . . . . . . . . .  6
     3.4.  Usage of RTP Extensions  . . . . . . . . . . . . . . . . .  6
     3.5.  Incremental Deployment . . . . . . . . . . . . . . . . . .  7
     3.6.  Summary  . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Support Use of Multiple RTP Sessions . . . . . . . . . . .  7
     4.2.  Same SSRC Value in Multiple RTP Sessions . . . . . . . . .  8
     4.3.  SRTP . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.4.  Don't Redefine Used Bits . . . . . . . . . . . . . . . . .  9
     4.5.  Firewall Friendly  . . . . . . . . . . . . . . . . . . . .  9
     4.6.  Monitoring and Reporting . . . . . . . . . . . . . . . . .  9
     4.7.  Usable Also Over Multicast . . . . . . . . . . . . . . . . 10
     4.8.  Incremental Deployment . . . . . . . . . . . . . . . . . . 10
   5.  Design Considerations  . . . . . . . . . . . . . . . . . . . . 10
     5.1.  Location of SHIM . . . . . . . . . . . . . . . . . . . . . 10
     5.2.  ICE and DTLS-SRTP Integration  . . . . . . . . . . . . . . 12
     5.3.  Signalling Fallback  . . . . . . . . . . . . . . . . . . . 12
   6.  Specification  . . . . . . . . . . . . . . . . . . . . . . . . 13
     6.1.  Shim Layer . . . . . . . . . . . . . . . . . . . . . . . . 14
     6.2.  Signalling . . . . . . . . . . . . . . . . . . . . . . . . 17
     6.3.  SRTP Key Management  . . . . . . . . . . . . . . . . . . . 18
       6.3.1.  Security Description . . . . . . . . . . . . . . . . . 19
       6.3.2.  DTLS-SRTP  . . . . . . . . . . . . . . . . . . . . . . 19
       6.3.3.  MIKEY  . . . . . . . . . . . . . . . . . . . . . . . . 19
     6.4.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . 20
       6.4.1.  RTP Packet with Transport Header . . . . . . . . . . . 20
       6.4.2.  SDP Offer/Answer example . . . . . . . . . . . . . . . 21
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