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RTP Retransmission Payload Format
RFC 4588

Document type: RFC - Proposed Standard (July 2006; Errata)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 4588 (Proposed Standard)
Responsible AD: Allison Mankin
Send notices to: <csp@csperkins.org>, <magnus.westerlund@ericsson.com>

Network Working Group                                             J. Rey
Request for Comments: 4588                                     Panasonic
Category: Standards Track                                        D. Leon
                                                              Consultant
                                                             A. Miyazaki
                                                               Panasonic
                                                                V. Varsa
                                                                   Nokia
                                                            R. Hakenberg
                                                               Panasonic
                                                               July 2006

                   RTP Retransmission Payload Format

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   RTP retransmission is an effective packet loss recovery technique for
   real-time applications with relaxed delay bounds.  This document
   describes an RTP payload format for performing retransmissions.
   Retransmitted RTP packets are sent in a separate stream from the
   original RTP stream.  It is assumed that feedback from receivers to
   senders is available.  In particular, it is assumed that Real-time
   Transport Control Protocol (RTCP) feedback as defined in the extended
   RTP profile for RTCP-based feedback (denoted RTP/AVPF) is available
   in this memo.

Rey, et al.                 Standards Track                     [Page 1]
RFC 4588           RTP Retransmission Payload Format           July 2006

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Requirements and Design Rationale for a Retransmission Scheme ...4
      3.1. Multiplexing Scheme Choice .................................6
   4. Retransmission Payload Format ...................................7
   5. Association of Retransmission and Original Streams ..............9
      5.1. Retransmission Session Sharing .............................9
      5.2. CNAME Use ..................................................9
      5.3. Association at the Receiver ................................9
   6. Use with the Extended RTP Profile for RTCP-based Feedback ......11
      6.1. RTCP at the Sender ........................................11
      6.2. RTCP Receiver Reports .....................................11
      6.3. Retransmission Requests ...................................12
      6.4. Timing Rules ..............................................13
   7. Congestion Control .............................................13
   8. Retransmission Payload Format MIME Type Registration ...........15
      8.1. Introduction ..............................................15
      8.2. Registration of audio/rtx .................................16
      8.3. Registration of video/rtx .................................17
      8.4. Registration of text/rtx ..................................18
      8.5. Registration of application/rtx ...........................19
      8.6. Mapping to SDP ............................................20
      8.7. SDP Description with Session-Multiplexing .................20
      8.8. SDP Description with SSRC-Multiplexing ....................21
   9. RTSP Considerations ............................................22
      9.1. RTSP Control with SSRC-Multiplexing .......................22
      9.2. RTSP Control with Session-Multiplexing ....................22
      9.3. RTSP Control of the Retransmission Stream .................23
      9.4. Cache Control .............................................23
   10. Implementation Examples .......................................23
      10.1. A Minimal Receiver Implementation Example ................24
      10.2. Retransmission of Layered Encoded Media in Multicast .....25
   11. IANA Considerations ...........................................26
   12. Security Considerations .......................................26
   13. Acknowledgements ..............................................27
   14. References ....................................................27
      14.1. Normative References .....................................27
      14.2. Informative References ...................................28
   Appendix A. How to Control the Number of Rtxs. per Packet .........29

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