Integration of Resource Management and Session Initiation Protocol (SIP)
RFC 3312

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 07

Network Working Group                                  G. Camarillo, Ed.
Request for Comments: 3312                                      Ericsson
Category: Standards Track                               W. Marshall, Ed.
                                                                    AT&T
                                                            J. Rosenberg
                                                             dynamicsoft
                                                            October 2002

                  Integration of Resource Management
                 and Session Initiation Protocol (SIP)

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 generic framework for preconditions, which
   are extensible through IANA registration.  This document also
   discusses how network quality of service can be made a precondition
   for establishment of sessions initiated by the Session Initiation
   Protocol (SIP).  These preconditions require that the participant
   reserve network resources before continuing with the session.  We do
   not define new quality of service reservation mechanisms; these
   preconditions simply require a participant to use existing resource
   reservation mechanisms before beginning the session.

Camarillo, et. al.          Standards Track                     [Page 1]
RFC 3312       Integration of Resource Management and SIP   October 2002

Table of Contents

   1 Introduction ...................................................  2
   2 Terminology ....................................................  3
   3 Overview .......................................................  3
   4 SDP parameters .................................................  4
   5 Usage of preconditions with offer/answer .......................  7
   5.1 Generating an offer ..........................................  8
   5.1.1 SDP encoding ...............................................  9
   5.2 Generating an Answer ......................................... 10
   6 Suspending and Resuming Session Establishment .................. 11
   7 Status Confirmation ............................................ 12
   8 Refusing an offer .............................................. 13
   8.1 Rejecting a Media Stream ..................................... 14
   9 Unknown Precondition Type ...................................... 15
   10 Multiple Preconditions per Media Stream ....................... 15
   11 Option Tag for Preconditions .................................. 16
   12 Indicating Capabilities ....................................... 16
   13 Examples ...................................................... 16
   13.1 End-to-end Status Type ...................................... 17
   13.2 Segmented Status Type ....................................... 21
   13.3 Offer in a SIP response ..................................... 23
   14 Security Considerations ....................................... 26
   15 IANA Considerations ........................................... 26
   16 Notice Regarding Intellectual Property Rights ................. 27
   17 References .................................................... 27
   18 Contributors .................................................. 28
   19 Acknowledgments ............................................... 28
   20 Authors' Addresses ............................................ 29
   21 Full Copyright Statement ...................................... 30

1 Introduction

   Some architectures require that at session establishment time, once
   the callee has been alerted, the chances of a session establishment
   failure are minimum.  One source of failure is the inability to
   reserve network resources for a session.  In order to minimize "ghost
   rings", it is necessary to reserve network resources for the session
   before the callee is alerted.  However, the reservation of network
   resources frequently requires learning the IP address, port, and
   session parameters from the callee.  This information is obtained as
   a result of the initial offer/answer exchange carried in SIP.  This
   exchange normally causes the "phone to ring", thus introducing a
   chicken-and-egg problem: resources cannot be reserved without
   performing an initial offer/answer exchange, and the initial
   offer/answer exchange can't be done without performing resource
   reservation.

Camarillo, et. al.          Standards Track                     [Page 2]
RFC 3312       Integration of Resource Management and SIP   October 2002