A Session Initiation Protocol (SIP) Event Package for Session-Specific Policies
RFC 6795

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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.

   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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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