The Session Initiation Protocol (SIP) P-Profile-Key Private Header (P-Header)
RFC 5002

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Network Working Group                                       G. Camarillo
Request for Comments: 5002                                     G. Blanco
Category: Informational                                         Ericsson
                                                             August 2007

                 The Session Initiation Protocol (SIP)
                P-Profile-Key Private Header (P-Header)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Abstract

   This document specifies the SIP P-Profile-Key P-header.  This header
   field is used in the 3rd-Generation Partnership Project (3GPP) IMS
   (IP Multimedia Subsystem) to provide SIP registrars and SIP proxy
   servers with the key of the profile corresponding to the destination
   SIP URI of a particular SIP request.

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................2
   3. Scenario ........................................................2
   4. Requirements ....................................................3
   5. P-Profile-Key Header Field Definition ...........................3
   6. Applicability ...................................................4
   7. IANA Considerations .............................................4
   8. Security Considerations .........................................5
   9. Acknowledgements ................................................5
   10. References .....................................................5
      10.1. Normative References ......................................5
      10.2. Informative References ....................................6

Author*                      Informational                      [Page 1]
RFC 5002                 P-Profile-Key P-Header              August 2007

1.  Introduction

   The 3rd-Generation Partnership Project (3GPP) IMS (IP Multimedia
   Subsystem) uses SIP [RFC3261] as its main signalling protocol.  (For
   more information on the IMS, a detailed description can be found in
   3GPP TS 23.228 [3GPP.23.228] and 3GPP TS 24.229 [3GPP.24.229]).  3GPP
   has identified a set of requirements that can be met, according to
   the procedures in [RFC3427], by defining a new SIP P-header.

   The remainder of this document is organized as follows.  Section 3
   describes the scenario considered by 3GPP and Section 4 discusses the
   requirements derived from this scenario.  Section 5 defines the P-
   Profile-Key header field, which meets those requirements, and Section
   6 discusses the applicability and scope of this new header field.
   Section 7 registers the P-Profile-Key header field with the IANA and
   Section 8 discusses the security properties of the environment where
   this header field is intended to be used.

2.  Terminology

   HSS:     Home Subscriber Server.

   I-CSCF:  Interrogating - Call/Session Control Function.

   Public Service Identity:
            A SIP URI that refers to a service instead of a user.

   S-CSCF:  Serving - Call/Session Control Function.

   Wildcarded Public Service Identity:
            A set of Public Service Identities that match a regular
            expression and share the same profile.

3.  Scenario

   In the 3GPP IMS, there are scenarios where a set of proxies handling
   a request need to consult the same user database, as described in
   [RFC4457].  Those proxies typically use the destination SIP URI of
   the request as the key for their database queries.  Nevertheless,
   when a proxy handles a Wildcarded Public Service Identity, the key to
   be used in its database query is not the destination SIP URI of the
   request, but a regular expression instead.

   Public Service Identities are SIP URIs that refer to services instead
   of users.  That is, they address a specific application in an
   Application Server.  Wildcarded Public Service Identities are a set
   of Public Service Identities that match a regular expression and
   share the same profile.  For example, the Public Service Identities

Author*                      Informational                      [Page 2]
RFC 5002                 P-Profile-Key P-Header              August 2007

   'sip:chatroom-12@example.com' and 'sip:chatroom-657@example.com'
   would match the Wildcarded Public Service Identity
   'sip:chatroom-!.*!@example.com'.  For a description of Wildcarded
   Public Service Identities, see 3GPP TS 23.003 [3GPP.23.003].

   When a proxy queries the user database for a Public Service Identity
   for which there is no profile in the user database, the user database
   needs to find its matching Wildcarded Public Service Identity.  For
   example, if the user database receives a query for
   'sip:chatroom-657@example.com', the user database needs to go through
   all the Wildcarded Public Service Identity it has until it finds a