Session Description Protocol (SDP) Capability Negotiation (RFC5939)
Original Publication Date: 2010-Sep-01
Included in the Prior Art Database: 2010-Sep-15
Internet Society Requests For Comment (RFCs)
The Session Description Protocol (SDP) was intended to describe multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. An SDP session description contains one or more media stream descriptions with information such as IP address and port, type of media stream (e.g., audio or video), transport protocol (possibly including profile information, e.g., RTP/AVP or RTP/SAVP), media formats (e.g., codecs), and various other session and media stream parameters that define the session.
Internet Engineering Task Force (IETF) F. Andreasen Request for Comments: 5939 Cisco Systems Category: Standards Track September 2010 ISSN: 2070-1721
Session Description Protocol (SDP) Capability Negotiation
The Session Description Protocol (SDP) was intended to describe multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. SDP was not intended to provide capability indication or capability negotiation; however, over the years, SDP has seen widespread adoption and as a result it has been gradually extended to provide limited support for these, notably in the form of the offer/answer model defined in RFC 3264. SDP does not define how to negotiate one or more alternative transport protocols (e.g., RTP profiles) or attributes. This makes it difficult to deploy new RTP profiles such as Secure RTP or RTP with RTCP-based feedback, negotiate use of different security keying mechanisms, etc. It also presents problems for some forms of media negotiation.
The purpose of this document is to address these shortcomings by extending SDP with capability negotiation parameters and associated offer/answer procedures to use those parameters in a backwards compatible manner.
The document defines a general SDP Capability Negotiation framework. It also specifies how to provide attributes and transport protocols as capabilities and negotiate them using the framework. Extensions for other types of capabilities (e.g., media types and media formats) may be provided in other documents.
Andreasen Standards Track [Page 1]
RFC 5939 SDP Capability Negotiation September 2010
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/rfc5939.
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