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