SDP: Session Description Protocol
RFC 2327
Document | Type |
RFC - Proposed Standard
(April 1998; Errata)
Obsoleted by RFC 4566
Updated by RFC 3266
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Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text pdf html bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 2327 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group M. Handley Request for Comments: 2327 V. Jacobson Category: Standards Track ISI/LBNL April 1998 SDP: Session Description Protocol Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1998). All Rights Reserved. Abstract This document defines the Session Description Protocol, SDP. SDP is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. This document is a product of the Multiparty Multimedia Session Control (MMUSIC) working group of the Internet Engineering Task Force. Comments are solicited and should be addressed to the working group's mailing list at confctrl@isi.edu and/or the authors. 1. Introduction On the Internet multicast backbone (Mbone), a session directory tool is used to advertise multimedia conferences and communicate the conference addresses and conference tool-specific information necessary for participation. This document defines a session description protocol for this purpose, and for general real-time multimedia session description purposes. This memo does not describe multicast address allocation or the distribution of SDP messages in detail. These are described in accompanying memos. SDP is not intended for negotiation of media encodings. Handley & Jacobson Standards Track [Page 1] RFC 2327 SDP April 1998 2. Background The Mbone is the part of the internet that supports IP multicast, and thus permits efficient many-to-many communication. It is used extensively for multimedia conferencing. Such conferences usually have the property that tight coordination of conference membership is not necessary; to receive a conference, a user at an Mbone site only has to know the conference's multicast group address and the UDP ports for the conference data streams. Session directories assist the advertisement of conference sessions and communicate the relevant conference setup information to prospective participants. SDP is designed to convey such information to recipients. SDP is purely a format for session description - it does not incorporate a transport protocol, and is intended to use different transport protocols as appropriate including the Session Announcement Protocol [4], Session Initiation Protocol [11], Real- Time Streaming Protocol [12], electronic mail using the MIME extensions, and the Hypertext Transport Protocol. SDP is intended to be general purpose so that it can be used for a wider range of network environments and applications than just multicast session directories. However, it is not intended to support negotiation of session content or media encodings - this is viewed as outside the scope of session description. 3. Glossary of Terms The following terms are used in this document, and have specific meaning within the context of this document. Conference A multimedia conference is a set of two or more communicating users along with the software they are using to communicate. Session A multimedia session is a set of multimedia senders and receivers and the data streams flowing from senders to receivers. A multimedia conference is an example of a multimedia session. Session Advertisement See session announcement. Session Announcement A session announcement is a mechanism by which a session description is conveyed to users in a proactive fashion, i.e., the session description was not explicitly requested by the user. Handley & Jacobson Standards Track [Page 2] RFC 2327 SDP April 1998 Session Description A well defined format for conveying sufficient information to discover and participate in a multimedia session. 3.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. 4. SDP Usage 4.1. Multicast Announcements SDP is a session description protocol for multimedia sessions. A common mode of usage is for a client to announce a conference sessionShow full document text