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Session Description Protocol (SDP) Capability Negotiation (RFC5939) Disclosure Number: IPCOM000199699D
Original Publication Date: 2010-Sep-01
Included in the Prior Art Database: 2010-Sep-15

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

F. Andreasen: AUTHOR


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.

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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

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    (