Delayed Duplication Attribute in the Session Description Protocol
draft-ietf-mmusic-delayed-duplication-01

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MMUSIC                                                          A. Begen
Internet-Draft                                                     Cisco
Intended status:  Standards Track                                 Y. Cai
Expires:  September 21, 2013                                   Microsoft
                                                                   H. Ou
                                                                   Cisco
                                                          March 20, 2013

   Delayed Duplication Attribute in the Session Description Protocol
                draft-ietf-mmusic-delayed-duplication-01

Abstract

   A straightforward approach to provide protection against packet
   losses due to network outages with a longest duration of T time units
   is to simply duplicate the original packets and send each copy
   separated in time by at least T time units.  This approach is
   commonly referred to as Time-shifted Redundancy, Temporal Redundancy
   or simply Delayed Duplication.  This document defines an attribute to
   indicate the presence of temporally redundant media streams and the
   duplication delay in the Session Description Protocol.

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 September 21, 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

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . . . 4
   3.  The 'duplication-delay' Attribute . . . . . . . . . . . . . . . 4
   4.  SDP Examples  . . . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
     6.1.  Registration of SDP Attributes  . . . . . . . . . . . . . . 7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9

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1.  Introduction

   Consider that a media sender transmits an original source packet and
   transmits its duplicate after a certain delay following the original
   transmission.  If a network outage hits the original transmission,
   the expectation is that the second transmission arrives at the
   receiver.  Alternatively, the second transmission may be hit by an
   outage and gets dropped, and the original transmission completes
   successfully.  On the receiver side, both transmissions can also
   arrive and in that case, the receiver (or the node that does the
   duplicate suppression) needs to identify the duplicate packets and
   discard them appropriately, producing a duplicate-free stream.

   Delayed duplication can be used in a variety of multimedia
   applications where there is sufficient bandwidth for the duplicated
   traffic and the application can tolerate the introduced delay.
   However, it must be used with care since it might easily result in a
   new series of denial-of-service attacks.  Furthermore, delayed
   duplication must not be used in cases where the primary cause of
   packet loss is congestion, rather than a network outage due to a