The Session Description Protocol (SDP) Grouping Framework
RFC 5888
| Document | Type |
RFC - Proposed Standard
(June 2010; Errata)
Obsoletes RFC 3388
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5888 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Cullen Jennings | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) G. Camarillo
Request for Comments: 5888 Ericsson
Obsoletes: 3388 H. Schulzrinne
Category: Standards Track Columbia University
ISSN: 2070-1721 June 2010
The Session Description Protocol (SDP) Grouping Framework
Abstract
In this specification, we define a framework to group "m" lines in
the Session Description Protocol (SDP) for different purposes. This
framework uses the "group" and "mid" SDP attributes, both of which
are defined in this specification. Additionally, we specify how to
use the framework for two different purposes: for lip synchronization
and for receiving a media flow consisting of several media streams on
different transport addresses. This document obsoletes RFC 3388.
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/rfc5888.
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
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.
Camarillo & Schulzrinne Standards Track [Page 1]
RFC 5888 SDP Grouping Framework June 2010
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of Operation . . . . . . . . . . . . . . . . . . . . 3
4. Media Stream Identification Attribute . . . . . . . . . . . . 4
5. Group Attribute . . . . . . . . . . . . . . . . . . . . . . . 4
6. Use of "group" and "mid" . . . . . . . . . . . . . . . . . . . 4
7. Lip Synchronization (LS) . . . . . . . . . . . . . . . . . . . 5
7.1. Example of LS . . . . . . . . . . . . . . . . . . . . . . 5
8. Flow Identification (FID) . . . . . . . . . . . . . . . . . . 6
8.1. SIP and Cellular Access . . . . . . . . . . . . . . . . . 6
8.2. DTMF Tones . . . . . . . . . . . . . . . . . . . . . . . . 7
8.3. Media Flow Definition . . . . . . . . . . . . . . . . . . 7
8.4. FID Semantics . . . . . . . . . . . . . . . . . . . . . . 7
8.4.1. Examples of FID . . . . . . . . . . . . . . . . . . . 8
8.5. Scenarios That FID Does Not Cover . . . . . . . . . . . . 11
8.5.1. Parallel Encoding Using Different Codecs . . . . . . . 11
8.5.2. Layered Encoding . . . . . . . . . . . . . . . . . . . 12
8.5.3. Same IP Address and Port Number . . . . . . . . . . . 12
9. Usage of the "group" Attribute in SIP . . . . . . . . . . . . 13
9.1. Mid Value in Answers . . . . . . . . . . . . . . . . . . . 13
9.1.1. Example . . . . . . . . . . . . . . . . . . . . . . . 14
9.2. Group Value in Answers . . . . . . . . . . . . . . . . . . 15
9.2.1. Example . . . . . . . . . . . . . . . . . . . . . . . 15
9.3. Capability Negotiation . . . . . . . . . . . . . . . . . . 16
9.3.1. Example . . . . . . . . . . . . . . . . . . . . . . . 16
9.4. Backward Compatibility . . . . . . . . . . . . . . . . . . 17
9.4.1. Offerer Does Not Support "group" . . . . . . . . . . . 17
9.4.2. Answerer Does Not Support "group" . . . . . . . . . . 17
10. Changes from RFC 3388 . . . . . . . . . . . . . . . . . . . . 18
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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