Support for Reduced-Size Real-Time Transport Control Protocol (RTCP): Opportunities and Consequences
RFC 5506

Document Type RFC - Proposed Standard (April 2009; Errata)
Last updated 2013-03-02
Replaces draft-johansson-avt-rtcp-avpf-non-compound
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IESG IESG state RFC 5506 (Proposed Standard)
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Responsible AD Cullen Jennings
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Network Working Group                                       I. Johansson
Request for Comments: 5506                                 M. Westerlund
Updates: 3550, 3711, 4585                                    Ericsson AB
Category: Standards Track                                     April 2009

 Support for Reduced-Size Real-Time Transport Control Protocol (RTCP):
                     Opportunities and Consequences

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) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   it for publication as an RFC or to translate it into languages other
   than English.

Johansson & Westerlund      Standards Track                     [Page 1]
RFC 5506            Reduced-Size RTCP in RTP Profile          April 2009

Abstract

   This memo discusses benefits and issues that arise when allowing
   Real-time Transport Protocol (RTCP) packets to be transmitted with
   reduced size.  The size can be reduced if the rules on how to create
   compound packets outlined in RFC 3550 are removed or changed.  Based
   on that analysis, this memo defines certain changes to the rules to
   allow feedback messages to be sent as Reduced-Size RTCP packets under
   certain conditions when using the RTP/AVPF (Real-time Transport
   Protocol / Audio-Visual Profile with Feedback) profile (RFC 4585).
   This document updates RFC 3550, RFC 3711, and RFC 4585.

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Use Cases and Design Rationale ..................................4
      3.1. RTCP Compound Packets (Background) .........................4
      3.2. Use Cases for Reduced-Size RTCP ............................6
      3.3. Benefits of Reduced-Size RTCP ..............................7
      3.4. Issues with Reduced-Size RTCP ..............................8
           3.4.1. Middle Boxes ........................................9
           3.4.2. Packet Validation ...................................9
           3.4.3. Encryption/Authentication ..........................10
           3.4.4. RTP and RTCP Multiplex on the Same Port ............10
           3.4.5. Header Compression .................................11
   4. Use of Reduced-Size RTCP with AVPF .............................11
      4.1. Definition of Reduced-Size RTCP ...........................12
      4.2. Algorithm Considerations ..................................12
           4.2.1. Verification of Delivery ...........................12
           4.2.2. Single vs Multiple RTCP in a Reduced-Size RTCP .....13
           4.2.3. Enforcing Compound RTCP ............................13
           4.2.4. Immediate Feedback Mode ............................14
   5. Signaling ......................................................14
   6. Security Considerations ........................................14
   7. IANA Considerations ............................................14
   8. Acknowledgements ...............................................15
   9. References .....................................................15
      9.1. Normative References ......................................15
      9.2. Informative References ....................................16

Johansson & Westerlund      Standards Track                     [Page 2]
RFC 5506            Reduced-Size RTCP in RTP Profile          April 2009
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