RFC 3312 (rfc3312) - Page 2 of 30
Integration of Resource Management and Session Initiation Protocol (SIP)
Alternative Format: Original Text Document
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