Session Initiation Protocol (SIP) Usage of the Offer/Answer Model
RFC 6337
Document | Type |
RFC - Informational
(August 2011; No errata)
Was draft-ietf-sipping-sip-offeranswer (individual in rai area)
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|
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Authors | Shinji OKUMURA , Takuya Sawada , Paul Kyzivat | ||
Last updated | 2015-10-14 | ||
Replaces | draft-sawada-sipping-sip-offeranswer | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6337 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Robert Sparks | ||
Send notices to | mary.ietf.barnes@gmail.com, sipping-chairs@ietf.org |
Internet Engineering Task Force (IETF) S. Okumura Request for Comments: 6337 Softfront Category: Informational T. Sawada ISSN: 2070-1721 KDDI Corporation P. Kyzivat August 2011 Session Initiation Protocol (SIP) Usage of the Offer/Answer Model Abstract The Session Initiation Protocol (SIP) utilizes the offer/answer model to establish and update multimedia sessions using the Session Description Protocol (SDP). The description of the offer/answer model in SIP is dispersed across multiple RFCs. This document summarizes all the current usages of the offer/answer model in SIP communication. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. 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). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see 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/rfc6337. Copyright Notice Copyright (c) 2011 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 Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Okumura, et al. Informational [Page 1] RFC 6337 SIP Usage of the Offer/Answer Model August 2011 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction ....................................................3 2. Summary of SIP Usage of the Offer/Answer Model ..................3 2.1. Terminology ................................................3 2.2. Offer/Answer Exchange Pairs in SIP Messages ................4 2.3. Rejection of an Offer ......................................5 2.4. Session Description That Is Not an Offer or an Answer ......7 3. Detailed Discussion of the Offer/Answer Model for SIP ...........8 3.1. Offer/Answer for the INVITE method with 100rel Extension ...8 3.1.1. INVITE Request with SDP .............................8 3.1.2. INVITE Request without SDP .........................11 3.2. Offer/Answer Exchange in Early Dialog .....................12 3.3. Offer/Answer Exchange in an Established Dialog ............12 3.4. Recovering from a Failed Re-INVITE ........................13 4. Exceptional Case Handling ......................................13 4.1. Message Crossing Case Handling ............................13 4.2. Glare Case Handling .......................................18 4.3. Interworking of UPDATE and Re-INVITE ......................21 5. Content of Offers and Answers ..................................25 5.1. General Principle for Constructing Offers and Answers .....26 5.2. Choice of Media Types and Formats to Include and Exclude ..26 5.2.1. Sending an Initial INVITE with Offer ...............26 5.2.2. Responding with an Offer When the Initial INVITE Has No Offer ................................27 5.2.3. Answering an Initial INVITE with Offer .............27 5.2.4. Answering When the Initial INVITE Had No Offer .....28 5.2.5. Subsequent Offers and Answers ......................28 5.3. Hold and Resume of Media ..................................29 5.4. Behavior on Receiving SDP with c=0.0.0.0 ..................31 6. Security Considerations ........................................31 7. Acknowledgements ...............................................31 8. References .....................................................32 8.1. Normative References ......................................32 8.2. Informative References ....................................33 Okumura, et al. Informational [Page 2] RFC 6337 SIP Usage of the Offer/Answer Model August 2011Show full document text