A Session Initiation Protocol (SIP) Event Package for Session-Specific Policies
RFC 6795
Internet Engineering Task Force (IETF) V. Hilt
Request for Comments: 6795 Bell Labs/Alcatel-Lucent
Category: Standards Track G. Camarillo
ISSN: 2070-1721 Ericsson
December 2012
A Session Initiation Protocol (SIP) Event Package for
Session-Specific Policies
Abstract
This specification defines a Session Initiation Protocol (SIP) event
package for session-specific policies. This event package enables
user agents (UAs) to subscribe to session policies for a SIP session
and to receive notifications if these policies change.
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/rfc6795.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Hilt & Camarillo Standards Track [Page 1]
RFC 6795 Session Policy Event Package December 2012
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Event Package Formal Definition .................................3
3.1. Event Package Name .........................................4
3.2. Event Package Parameters ...................................4
3.3. SUBSCRIBE Bodies ...........................................4
3.4. Subscription Duration ......................................5
3.5. NOTIFY Bodies ..............................................5
3.6. Subscriber Generation of SUBSCRIBE Requests ................6
3.7. Notifier Processing of SUBSCRIBE Requests ..................8
3.8. Notifier Generation of NOTIFY Requests .....................9
3.9. Subscriber Processing of NOTIFY Requests ..................10
3.10. Handling of Forked Requests ..............................11
3.11. Rate of Notifications ....................................11
3.12. State Agents .............................................11
3.13. Examples .................................................11
4. Security Considerations ........................................14
5. IANA Considerations ............................................16
5.1. Event Package Name ........................................16
6. References .....................................................16
6.1. Normative References ......................................16
6.2. Informative References ....................................17
Appendix A. Acknowledgements ......................................18
1. Introduction
The Framework for Session Initiation Protocol (SIP) [RFC3261] Session
Policies [RFC6794] defines a protocol framework that enables a proxy
to define and impact policies on sessions such as the codecs or media
types to be used. This framework identifies two types of session
policies: session-specific and session-independent policies.
Session-specific policies are policies that are created for one
particular session, based on the session description of this session.
They enable a network intermediary to inspect the session description
that a UA is proposing and to return a policy specifically generated
for this session description. For example, an intermediary could
open pinholes in a firewall/NAT for each media stream in a session
and return a policy that replaces the internal IP addresses and ports
in the session description with external ones. Since session-
specific policies are tailored to a session, they only apply to the
session for which they are created. A UA requests session-specific
policies on a session-by-session basis at the time a session is
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