RTP Control Protocol (RTCP) Extensions for Single-Source Multicast Sessions with Unicast Feedback
RFC 5760

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Internet Engineering Task Force (IETF)                            J. Ott
Request for Comments: 5760                              Aalto University
Category: Standards Track                                J. Chesterfield
ISSN: 2070-1721                                  University of Cambridge
                                                             E. Schooler
                                                                   Intel
                                                           February 2010

               RTP Control Protocol (RTCP) Extensions for
         Single-Source Multicast Sessions with Unicast Feedback

Abstract

   This document specifies an extension to the Real-time Transport
   Control Protocol (RTCP) to use unicast feedback to a multicast
   sender.  The proposed extension is useful for single-source multicast
   sessions such as Source-Specific Multicast (SSM) communication where
   the traditional model of many-to-many group communication is either
   not available or not desired.  In addition, it can be applied to any
   group that might benefit from a sender-controlled summarized
   reporting mechanism.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5760.

Copyright Notice

   Copyright (c) 2010 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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must

Ott, et al.                  Standards Track                    [Page 1]
RFC 5760               RTCP with Unicast Feedback          February 2010

   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
   2. Conventions and Acronyms ........................................4
   3. Definitions .....................................................5
   4. Basic Operation .................................................6
   5. Packet Types ...................................................10
   6. Simple Feedback Model ..........................................11
   7. Distribution Source Feedback Summary Model .....................13
   8. Mixer/Translator Issues ........................................36
   9. Transmission Interval Calculation ..............................37
   10. SDP Extensions ................................................39
   11. Security Considerations .......................................41
   12. Backwards Compatibility .......................................51
   13. IANA Considerations ...........................................51
   14. References ....................................................53
   Appendix A. Examples for Sender-Side Configurations ...............57
   Appendix B. Distribution Report Processing at the Receiver ........60

Ott, et al.                  Standards Track                    [Page 2]
RFC 5760               RTCP with Unicast Feedback          February 2010

1.  Introduction

   The Real-time Transport Protocol (RTP) [1] provides a real-time
   transport mechanism suitable for unicast or multicast communication
   between multimedia applications.  Typical uses of RTP are for real-
   time or near real-time group communication of audio and video data
   streams.  An important component of the RTP protocol is the control