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 | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| 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
identifier and a 16-bit length field specifying the length of the
header extension in 32-bit words.
This mechanism has two conspicuous drawbacks. First, it permits only
one header extension in a single RTP packet. Second, the
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