Miscellaneous Capabilities Negotiation in the Session Description Protocol (SDP)
RFC 7006

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Internet Engineering Task Force (IETF)                  M. Garcia-Martin
Request for Comments: 7006                                      Ericsson
Category: Standards Track                                S. Veikkolainen
ISSN: 2070-1721                                                    Nokia
                                                               R. Gilman
                                                          September 2013

             Miscellaneous Capabilities Negotiation in the
                   Session Description Protocol (SDP)

Abstract

   The Session Description Protocol (SDP) has been extended with a
   capability negotiation mechanism framework that allows the endpoints
   to negotiate transport protocols and attributes.  This framework has
   been extended with a media capabilities negotiation mechanism that
   allows endpoints to negotiate additional media-related capabilities.
   This negotiation is embedded into the widely used SDP offer/answer
   procedures.

   This memo extends the SDP capability negotiation framework to allow
   endpoints to negotiate three additional SDP capabilities.  In
   particular, this memo provides a mechanism to negotiate bandwidth
   ("b=" line), connection data ("c=" line), and session or media titles
   ("i=" line for each session or media).

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/rfc7006.

Garcia-Martin, et al.        Standards Track                    [Page 1]
RFC 7006           SDP Misc. Capabilities Negotiation     September 2013

Copyright Notice

   Copyright (c) 2013 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
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   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Conventions Used in This Document ...............................3
   3. Protocol Description ............................................4
      3.1. Extensions to SDP ..........................................4
           3.1.1. Bandwidth Capability ................................6
           3.1.2. Connection Data Capability ..........................8
           3.1.3. Title Capability ...................................12
      3.2. Session Level versus Media Level ..........................16
      3.3. Offer/Answer Model Extensions .............................17
           3.3.1. Generating the Initial Offer .......................17
           3.3.2. Generating the Answer ..............................17
           3.3.3. Offerer Processing of the Answer ...................18
           3.3.4. Modifying the Session ..............................18
   4. Field Replacement Rules ........................................18
   5. Security Considerations ........................................18
   6. IANA Considerations ............................................19
      6.1. New SDP Attributes ........................................19
      6.2. New Option Tags ...........................................20
      6.3. New SDP Capability Negotiation Configuration Parameters ...20
   7. Acknowledgments ................................................20
   8. References .....................................................20
      8.1. Normative References ......................................20
      8.2. Informative References ....................................21

Garcia-Martin, et al.        Standards Track                    [Page 2]
RFC 7006           SDP Misc. Capabilities Negotiation     September 2013

1.  Introduction

   The Session Description Protocol (SDP) [RFC4566] is intended for
   describing multimedia sessions for the purposes of session
   announcement, session invitation, and other forms of multimedia
   session initiation.  SDP has been extended with an SDP Capability
   Negotiation Mechanism Framework [RFC5939] that allows the endpoints
   to negotiate capabilities, such as support for the Real-time