A Framework for Session Initiation Protocol (SIP) Session Policies
RFC 6794
Internet Engineering Task Force (IETF) V. Hilt
Request for Comments: 6794 Bell Labs/Alcatel-Lucent
Category: Standards Track G. Camarillo
ISSN: 2070-1721 Ericsson
J. Rosenberg
jdrosen.net
December 2012
A Framework for Session Initiation Protocol (SIP) Session Policies
Abstract
Proxy servers play a central role as an intermediary in the Session
Initiation Protocol (SIP) as they define and impact policies on call
routing, rendezvous, and other call features. This document
specifies a framework for SIP session policies that provides a
standard mechanism by which a proxy can define or influence policies
on sessions, such as the codecs or media types to be used. It
defines a model, an overall architecture and new protocol mechanisms
for session policies.
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/rfc6794.
Copyright Notice
Copyright (c) 2012 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
Hilt, et al. Standards Track [Page 1]
RFC 6794 Session Policy Framework December 2012
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. Terminology .....................................................5
3. Session-Independent Policies ....................................5
3.1. Architecture and Overview ..................................5
3.2. Policy Subscription ........................................6
3.2.1. User Agent Client (UAC) Behavior ....................6
3.2.2. User Agent Server (UAS) Behavior ....................8
4. Session-Specific Policies .......................................8
4.1. Architecture ...............................................8
4.2. Overview ...................................................9
4.3. Examples ..................................................11
4.3.1. Offer in Request ...................................11
4.3.2. Offer in Response ..................................13
4.4. UA/Policy Server Rendezvous ...............................15
4.4.1. UAC Behavior .......................................15
4.4.2. Proxy Behavior .....................................17
4.4.3. UAS Behavior .......................................20
4.4.4. Caching the Local Policy Server URI ................21
4.4.5. Header Field Definition and Syntax .................22
4.5. Policy Channel ............................................23
4.5.1. Creation and Management ............................24
4.5.2. Contacting the Policy Server .......................25
4.5.3. Using Session Policies .............................26
5. Security Considerations ........................................27
6. IANA Considerations ............................................29
6.1. Registration of the "Policy-ID" Header Field ..............29
6.2. Registration of the "Policy-Contact" Header Field .........29
6.3. Registration of the "non-cacheable" Policy-Contact
Header Field Parameter ....................................29
6.4. Registration of the "policy" SIP Option Tag ...............29
7. References .....................................................30
7.1. Normative References ......................................30
7.2. Informative References ....................................31
Appendix A. Acknowledgements ......................................32
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