RFC 3312 (rfc3312) - Page 2 of 30

Integration of Resource Management and Session Initiation Protocol (SIP)

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