Framework for Session Set-up with Media Authorization
RFC 3521

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Network Working Group                                         L-N. Hamer
Request for Comments: 3521                                       B. Gage
Category: Informational                                  Nortel Networks
                                                                H. Shieh
                                                           AT&T Wireless
                                                              April 2003

         Framework for Session Set-up with 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

   Establishing multimedia streams must take into account requirements
   for end-to-end QoS, authorization of network resource usage and
   accurate accounting for resources used.  During session set up,
   policies may be enforced to ensure that the media streams being
   requested lie within the bounds of the service profile established
   for the requesting host.  Similarly, when a host requests resources
   to provide a certain QoS for a packet flow, policies may be enforced
   to ensure that the required resources lie within the bounds of the
   resource profile established for the requesting host.

   To prevent fraud and to ensure accurate billing, this document
   describes various scenarios and mechanisms that provide the linkage
   required to verify that the resources being used to provide a
   requested QoS are in-line with the media streams requested (and
   authorized) for the session.

Hamer, et al.                Informational                      [Page 1]
RFC 3521        Session Set-up with Media Authorization       April 2003

Table of Contents

   1.  Introduction....................................................2
   2.  Conventions used in this document...............................3
   3.  Definition of terms.............................................4
   4.  The Coupled Model...............................................5
       4.1   Coupled Model Message Flows...............................6
       4.2   Coupled Model Authorization Token.........................8
       4.3   Coupled Model Protocol Impacts............................8
   5.  The Associated Model <<using One Policy Server>>................8
       5.1   Associated Model Message Flows
             <<using One Policy Server>>...............................9
       5.2   Associated Model Authorization Token
             <<using One Policy Server>>..............................11
       5.3   Associated Model Protocol Impacts
             <<using One Policy Server>>..............................11
       5.4   Associated Model Network Impacts
             <<using One Policy Server>>..............................12
   6.  The Associated Model <<using Two Policy Servers>>..............12
       6.1   Associated Model Message Flows
             <<using Two Policy Servers>>.............................13
       6.2   Associated Model Authorization Token
             <<using Two Policy Servers>>.............................15
       6.3   Associated Model Protocol Impacts
             <<using Two Policy Servers>>.............................16
   7. The Non-Associated Model........................................16
       7.1   Non-Associated Model Message Flow........................17
       7.2   Non-Associated Model Authorization Token.................19
       7.3   Non-Associated Model Protocol Impacts....................19
   8.  Conclusions....................................................20
   9.  Security Considerations........................................21
   10. Normative References...........................................22
   11. Informative References.........................................23
   12. Acknowledgments................................................23
   13. Authors' Addresses.............................................24
   14. Full Copyright Statement.......................................25

1. Introduction

   Various mechanisms have been defined through which end hosts can use
   a session management protocol (e.g., SIP [6]) to indicate that QoS
   requirements must be met in order to successfully set up a session.
   However, a separate protocol (e.g., RSVP [7]) is used to request the
   resources required to meet the end-to-end QoS of the media stream.
   To prevent fraud and to ensure accurate billing, some linkage is

Hamer, et al.                Informational                      [Page 2]
RFC 3521        Session Set-up with Media Authorization       April 2003

   required to verify that the resources being used to provide the
   requested QoS are in-line with the media streams requested (and
   authorized) for the session.

   This document describes such a linkage through use of a "token" that