A General Mechanism for RTP Header Extensions
RFC 8285

Document Type RFC - Proposed Standard (October 2017; No errata)
Obsoletes RFC 5285
Last updated 2017-10-25
Replaces draft-even-avtcore-rfc5285-bis
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication (wg milestone: Sep 2016 - Submit update for A ... )
Document shepherd Magnus Westerlund
Shepherd write-up Show (last changed 2017-03-07)
IESG IESG state RFC 8285 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Ben Campbell
Send notices to "Magnus Westerlund" <magnus.westerlund@ericsson.com>
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                         D. Singer
Request for Comments: 8285                                   Apple, Inc.
Obsoletes: 5285                                              H. Desineni
Category: Standards Track                                       Qualcomm
ISSN: 2070-1721                                             R. Even, Ed.
                                                     Huawei Technologies
                                                            October 2017

             A General Mechanism for RTP Header Extensions

Abstract

   This document provides a general mechanism to use the header
   extension feature of RTP (the Real-time Transport Protocol).  It
   provides the option to use a small number of small extensions in each
   RTP packet, where the universe of possible extensions is large and
   registration is decentralized.  The actual extensions in use in a
   session are signaled in the setup information for that session.  This
   document obsoletes RFC 5285.

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 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8285.

Singer, et al.               Standards Track                    [Page 1]
RFC 8285                  RTP Header Extensions             October 2017

Copyright Notice

   Copyright (c) 2017 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
   (https://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
   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.

Table of Contents

   1. Introduction ....................................................3
   2. Requirements Notation ...........................................3
   3. Design Goals ....................................................3
   4. Packet Design ...................................................4
      4.1. General ....................................................4
           4.1.1. Transmission Considerations .........................5
           4.1.2. Header Extension Type Considerations ................6
      4.2. One-Byte Header ............................................8
      4.3. Two-Byte Header ............................................9
   5. SDP Signaling Design ...........................................10
   6. SDP Signaling for Support of Mixed One-Byte and Two-Byte
          Header Extensions ..........................................12
   7. SDP Offer/Answer ...............................................13
   8. BNF Syntax .....................................................17
   9. Security Considerations ........................................17
   10. IANA Considerations ...........................................18
      10.1. Identifier Space for IANA to Manage ......................18
      10.2. Registration of the SDP "extmap" Attribute ...............20
      10.3. Registration of the SDP "extmap-allow-mixed" Attribute ...20
   11. Changes from RFC 5285 .........................................21
   12. References ....................................................21
      12.1. Normative References .....................................21
      12.2. Informative References ...................................23
   Acknowledgments ...................................................24
   Authors' Addresses ................................................25

Singer, et al.               Standards Track                    [Page 2]
RFC 8285                  RTP Header Extensions             October 2017

1.  Introduction

   The RTP specification [RFC3550] provides a capability to extend the
   RTP header.  Section 5.3.1 of [RFC3550] defines the header extension
   format and rules for its use.  The existing header extension method
   permits at most one extension per RTP packet, identified by a 16-bit
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