Private Session Initiation Protocol (SIP) Extensions for Media Authorization
RFC 3313

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Network Working Group                                   W. Marshall, Ed.
Request for Comments: 3313                                          AT&T
Category: Informational                                     January 2003

          Private Session Initiation Protocol (SIP) Extensions
                        for Media Authorization

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.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes the need for Quality of Service (QoS) and
   media authorization and defines a Session Initiation Protocol (SIP)
   extension that can be used to integrate QoS admission control with
   call signaling and help guard against denial of service attacks.  The
   use of this extension is only applicable in administrative domains,
   or among federations of administrative domains with previously
   agreed-upon policies, where both the SIP proxy authorizing the QoS,
   and the policy control of the underlying network providing the QoS,
   belong to that administrative domain or federation of domains.

Marshall, Ed.                Informational                      [Page 1]
RFC 3313         SIP Extensions for Media Authorization     January 2003

Table of Contents

   1. Scope of Applicability.........................................  2
   2. Conventions Used in this Document..............................  3
   3. Background and Motivation......................................  3
   4. Overview.......................................................  4
   5. Changes to SIP to Support Media Authorization..................  4
      5.1 SIP Header Extension.......................................  5
      5.2 SIP Procedures.............................................  5
        5.2.1 User Agent Client (UAC)................................  6
        5.2.2 User Agent Server (UAS)................................  6
        5.2.3 Originating Proxy (OP).................................  7
        5.2.4 Destination Proxy (DP).................................  7
   6. Examples.......................................................  8
      6.1 Requesting Bandwidth via RSVP Messaging....................  8
        6.1.1 User Agent Client Side.................................  8
        6.1.2 User Agent Server Side................................. 10
   7. Advantages of the Proposed Approach............................ 12
   8. Security Considerations........................................ 13
   9. IANA Considerations............................................ 13
   10. Notice Regarding Intellectual Property Rights................. 13
   11. Normative References.......................................... 14
   12. Informative References........................................ 14
   13. Contributors.................................................. 15
   14. Acknowledgments............................................... 15
   15. Editor's Address.............................................. 15
   16. Full Copyright Statement...................................... 16

1. Scope of Applicability

   This document defines a SIP extension that can be used to integrate
   QoS admission control with call signaling and help guard against
   denial of service attacks.  The use of this extension is only
   applicable in administrative domains, or among federations of
   administrative domains with previously agreed-upon policies, where
   both the SIP proxy authorizing the QoS, and the policy control of the
   underlying network providing the QoS, belong to that administrative
   domain or federation of domains.  Furthermore, the mechanism is
   generally incompatible with end-to-end encryption of message bodies
   that describe media sessions.

   This is in contrast with general Internet principles, which separate
   data transport from applications.  Thus, the solution described in
   this document is not applicable to the Internet at large.  Despite
   these limitations, there are sufficiently useful specialized
   deployments that meet the assumptions described above, and can accept
   the limitations that result, to warrant informational publication of
   this mechanism.  An example deployment would be a closed network,

Marshall, Ed.                Informational                      [Page 2]
RFC 3313         SIP Extensions for Media Authorization     January 2003

   which emulates a traditional circuit switched telephone network.
   This document specifies a private header, facilitating use in these
   specialized configurations.

2. Conventions Used in this Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2].