Identification of Communications Services in the Session Initiation Protocol (SIP)
RFC 5897

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Internet Engineering Task Force (IETF)                      J. Rosenberg
Request for Comments: 5897                                   jdrosen.net
Category: Informational                                        June 2010
ISSN: 2070-1721

               Identification of Communications Services
                in the Session Initiation Protocol (SIP)

Abstract

   This document considers the problem of service identification in the
   Session Initiation Protocol (SIP).  Service identification is the
   process of determining the user-level use case that is driving the
   signaling being utilized by the user agent (UA).  This document
   discusses the uses of service identification, and outlines several
   architectural principles behind the process.  It identifies perils
   when service identification is not done properly -- including fraud,
   interoperability failures, and stifling of innovation.  It then
   outlines a set of recommended practices for service identification.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc5897.

Copyright Notice

   Copyright (c) 2010 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
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must

Rosenberg                     Informational                     [Page 1]
RFC 5897                    Service ID in SIP                  June 2010

   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Services and Service Identification .............................4
   3. Example Services ................................................6
      3.1. IPTV vs. Multimedia ........................................6
      3.2. Gaming vs. Voice Chat ......................................7
      3.3. Gaming vs. Voice Chat #2 ...................................7
      3.4. Configuration vs. Pager Messaging ..........................7
   4. Using Service Identification ....................................8
      4.1. Application Invocation in the User Agent ...................8
      4.2. Application Invocation in the Network ......................9
      4.3. Network Quality-of-Service Authorization ..................10
      4.4. Service Authorization .....................................10
      4.5. Accounting and Billing ....................................11
      4.6. Negotiation of Service ....................................11
      4.7. Dispatch to Devices .......................................11
   5. Key Principles of Service Identification .......................12
      5.1. Services Are a By-Product of Signaling ....................12
      5.2. Identical Signaling Produces Identical Services ...........13
      5.3. Do What I Say, Not What I Mean ............................14
      5.4. Declarative Service Identifiers Are Redundant .............15
      5.5. URIs Are Key for Differentiated Signaling .................15
   6. Perils of Declarative Service Identification ...................16
      6.1. Fraud .....................................................16
      6.2. Systematic Interoperability Failures ......................17
      6.3. Stifling of Service Innovation ............................18
   7. Recommendations ................................................20
      7.1. Use Derived Service Identification ........................20
      7.2. Design for SIP's Negotiative Expressiveness ...............20
      7.3. Presence ..................................................21
      7.4. Intra-Domain ..............................................21
      7.5. Device Dispatch ...........................................21
   8. Security Considerations ........................................22
   9. Acknowledgements ...............................................22
   10. Informative References ........................................22