Duplicating RTP Streams
draft-ietf-avtext-rtp-duplication-00

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Last updated 2012-07-03
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AVTEXT                                                          A. Begen
Internet-Draft                                                     Cisco
Intended status:  Standards Track                             C. Perkins
Expires:  January 3, 2013                          University of Glasgow
                                                            July 2, 2012

                        Duplicating RTP Streams
                  draft-ietf-avtext-rtp-duplication-00

Abstract

   Packet loss is undesirable for real-time multimedia sessions, but can
   occur due to congestion, or other unplanned network outages.  This is
   especially true for IP multicast networks, where packet loss patterns
   can vary greatly between receivers.  One technique that can be used
   to recover from packet loss without incurring unbounded delay for all
   the receivers is to duplicate the packets and send them in separate
   redundant streams.  This document explains how Real-time Transport
   Protocol (RTP) streams can be duplicated without breaking RTP media
   streams, or RTP Control Protocol (RTCP) rules.

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
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   This Internet-Draft will expire on January 3, 2013.

Copyright Notice

   Copyright (c) 2012 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

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   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.  Terminology and Requirements Notation  . . . . . . . . . . . .  3
   3.  Dual Streaming Use Cases . . . . . . . . . . . . . . . . . . .  3
     3.1.  Temporal Redundancy  . . . . . . . . . . . . . . . . . . .  4
     3.2.  Spatial Redundancy . . . . . . . . . . . . . . . . . . . .  4
     3.3.  Dual Streaming over a Single Path or Multiple Paths  . . .  5
   4.  Use of RTP and RTCP with Temporal Redundancy . . . . . . . . .  6
     4.1.  RTCP Considerations  . . . . . . . . . . . . . . . . . . .  6
     4.2.  Signaling Considerations . . . . . . . . . . . . . . . . .  6
   5.  Use of RTP and RTCP with Spatial Redundancy  . . . . . . . . .  7
     5.1.  RTCP Considerations  . . . . . . . . . . . . . . . . . . .  8
     5.2.  Signaling Considerations . . . . . . . . . . . . . . . . .  8
   6.  Use of RTP and RTCP with Temporal and Spatial Redundancy . . .  9
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
     10.2. Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11

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1.  Introduction

   The Real-time Transport Protocol (RTP) [RFC3550] is widely used today
   for delivering IPTV traffic, and other real-time multimedia sessions.
   Many of these applications support very large numbers of receivers,
   and rely on intra-domain UDP/IP multicast for efficient distribution
   of traffic within the network.

   While this combination has proved successful, there does exist a
   weakness.  As [RFC2354] noted, packet loss is not avoidable, even in
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