Negotiating Media Multiplexing Using the Session Description Protocol (SDP)
RFC 8843
Internet Engineering Task Force (IETF) C. Holmberg
Request for Comments: 8843 Ericsson
Updates: 3264, 5888, 7941 H. Alvestrand
Category: Standards Track Google
ISSN: 2070-1721 C. Jennings
Cisco
January 2021
Negotiating Media Multiplexing Using the Session Description Protocol
(SDP)
Abstract
This specification defines a new Session Description Protocol (SDP)
Grouping Framework extension called 'BUNDLE'. The extension can be
used with the SDP offer/answer mechanism to negotiate the usage of a
single transport (5-tuple) for sending and receiving media described
by multiple SDP media descriptions ("m=" sections). Such transport
is referred to as a BUNDLE transport, and the media is referred to as
bundled media. The "m=" sections that use the BUNDLE transport form
a BUNDLE group.
This specification defines a new RTP Control Protocol (RTCP) Source
Description (SDES) item and a new RTP header extension.
This specification updates RFCs 3264, 5888, and 7941.
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/rfc8843.
Copyright Notice
Copyright (c) 2021 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.
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
1.1. Background
1.2. BUNDLE Mechanism
1.3. Protocol Extensions
1.4. Contradiction regarding bundle-only "m=" sections
2. Terminology
3. Conventions
4. Applicability Statement
5. SDP Grouping Framework BUNDLE Extension
6. SDP 'bundle-only' Attribute
7. SDP Offer/Answer Procedures
7.1. Generic SDP Considerations
7.1.1. Connection Data ("c=")
7.1.2. Bandwidth ("b=")
7.1.3. Attributes ("a=")
7.2. Generating the Initial SDP Offer
7.2.1. Suggesting the Offerer-Tagged 'm=' Section
7.2.2. Example: Initial SDP Offer
7.3. Generating the SDP Answer
7.3.1. Answerer Selection of Tagged 'm=' Sections
7.3.2. Moving a Media Description Out of a BUNDLE Group
7.3.3. Rejecting a Media Description in a BUNDLE Group
7.3.4. Example: SDP Answer
7.4. Offerer Processing of the SDP Answer
7.5. Modifying the Session
7.5.1. Adding a Media Description to a BUNDLE Group
7.5.2. Moving a Media Description Out of a BUNDLE Group
7.5.3. Disabling a Media Description in a BUNDLE Group
8. Protocol Identification
8.1. STUN, DTLS, and SRTP
9. RTP Considerations
9.1. Single RTP Session
9.1.1. Payload Type (PT) Value Reuse
9.2. Associating RTP/RTCP Streams with the Correct SDP Media
Description
9.3. RTP/RTCP Multiplexing
9.3.1. SDP Offer/Answer Procedures
10. ICE Considerations
11. DTLS Considerations
12. RTP Header Extensions Consideration
13. Update to RFC 3264
13.1. Original Text from RFC 3264, Section 5.1, 2nd Paragraph
Show full document text