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Session Description Protocol (SDP) Simple Capability Declaration (RFC3407)

IP.com Disclosure Number: IPCOM000010082D
Original Publication Date: 2002-Oct-01
Included in the Prior Art Database: 2002-Oct-17
Document File: 11 page(s) / 21K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

F. Andreasen: AUTHOR

Abstract

This document defines a set of Session Description Protocol (SDP) attributes that enables SDP to provide a minimal and backwards compatible capability declaration mechanism. Such capability declarations can be used as input to a subsequent session negotiation, which is done by means outside the scope of this document. This provides a simple and limited solution to the general capability negotiation problem being addressed by the next generation of SDP, also known as SDPng.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 14% of the total text.

Network Working Group                                       F. Andreasen

Request for Comments: 3407                                 Cisco Systems

Category: Standards Track                                   October 2002

   Session Description Protocol (SDP) Simple Capability Declaration

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 (2002).  All Rights Reserved.

Abstract

   This document defines a set of Session Description Protocol (SDP)

   attributes that enables SDP to provide a minimal and backwards

   compatible capability declaration mechanism.  Such capability

   declarations can be used as input to a subsequent session

   negotiation, which is done by means outside the scope of this

   document.  This provides a simple and limited solution to the general

   capability negotiation problem being addressed by the next generation

   of SDP, also known as SDPng.

1. Conventions Used in this Document

   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 [2].

2. Introduction

   The Session Description Protocol (SDP) [3] describes multimedia

   sessions for the purposes of session announcement, session

   invitation, and other forms of multimedia session initiation.  SDP

   was not intended to provide capability negotiation.  However, as the

   need for this has become increasingly important, work has begun on a

   "next generation SDP" (SDPng) [4,5] that supports both session

   description and capability negotiation.  SDPng is not anticipated to

   be backwards compatible with SDP and work on SDPng is currently in

   the early stages.  However, several other protocols, e.g. SIP [6] and

   Media Gateway Control Protocol (MGCP) [7], use SDP and are likely to

Andreasen                   Standards Track                     [Page 1]

RFC 3407           SDP Simple Capability Declaration        October 2002

   continue doing so for the foreseeable future.  Nevertheless, in many

   cases these signaling protocols have an urgent need for some limited

   form of capability negotiation.

   For example, an endpoint may support G.711 audio (over RTP) as well

   as T.38 fax relay (over UDP or TCP).  Unless the endpoint is willing

   to support two media streams at the same time, this cannot currently

   be expressed in SDP.  Another example involves supp...