One document matched: draft-jesske-dispatch-reason-in-responses-02.txt

Differences from draft-jesske-dispatch-reason-in-responses-01.txt

dispatch                                                       R. Jesske
Internet-Draft                                                  L. Liess
Intended status: Informational                          Deutsche Telekom
Expires: October 1, 2010                                  March 30, 2010


   Reason header filed in Session Initiation Protocol (SIP) responses
              draft-jesske-dispatch-reason-in-responses-02

Abstract

   Although the use of the Reason header field in responses is
   considered in RFC3326, doing so is not specified for any existing
   response code.  Nonetheless, the Reason header field has been widely
   used in responses to carry Q.850 reason codes for failure responses
   to INVITEs that have been gatewayed to PSTN systems.  This document
   specifies and formally permits the use of the Reason header field in
   SIP responses to carry Q.850 reason codes for this and other
   purposes.

Status of this Memo

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Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Overall Applicability . . . . . . . . . . . . . . . . . . . . . 4
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     4.1.  Procedures at the UA  . . . . . . . . . . . . . . . . . . . 4
     4.2.  Procedures at a SIP proxy . . . . . . . . . . . . . . . . . 5
     4.3.  Procedures at an application server . . . . . . . . . . . . 5
   5.  Procedures at an interworking point with ISUP . . . . . . . . . 5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   8.  Normative References  . . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6





































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1.  Terminology

   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 [RFC2119].

   This document uses terms from [RFC3261].


2.  Overview

   Within [draft-jesske-dispatch-requirements-reason-in-responses-00]
   the reasoning and requirements for the use of the Reason Header
   within Responses is described.  Based upon this document describes
   the procedures for the use of the Reason header within responses.


3.  Overall Applicability

   The SIP procedures specified in this document are foreseen for
   networks providing simulation services and/or interworking to the
   PSTN/ISDN.

   The document is describing the use of the Reason header in SIP
   responses.  These procedures are only valuable if the reason
   contained in the element "protocol" is "Q.850".  A inclusion of a SIP
   reason (protocol="SIP") is not helpful due to the fact that the
   response already provides the SIP reason.  The Release Causes are
   described within [Q.850].  (Note: The ETSI specifications can be
   downloaded under http://pda.etsi.org/pda/queryform.asp free of
   charge.)

   The appearance of the Reason header is applicable to final responses
   3xx, 4xx, 5xx and 6xx and 18x and 199 provisional responses
   [I-D.ietf-sipcore-199].


4.  Procedures

4.1.  Procedures at the UA

   A UA that supports the Reason header field can process the [Q.850]
   Cause Value and display it or an equivalent text.  The inclusion of a
   Reason header field by UA is only for B2B UA interworking with the
   PSTN/ISDN or providing services foreseen.






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4.2.  Procedures at a SIP proxy

   SIP proxies that receive a response containing a Reason header field
   is forwarding the response without changing the reason.

   A SIP proxy receiving a request that includes a Reason header field
   can route the request to an application server for further analysis
   and base services on it.

   Based on network policy a Proxy can remove a Reason header field send
   from a UAC.

4.3.  Procedures at an application server

   An application server that receives a SIP request that contains a
   response including a Reason header MAY analyze the SIP Reason and
   base further procedures on this analyses.

   For Example the application server could use the reason for sending a
   announcement towards the originating entity of the session.

   As an example the Anonymous Communication Rejection (ACR) service
   defined by ETSI Telecommunications and Internet converged Services
   and Protocols for Advanced Networking (TISPAN)


5.  Procedures at an interworking point with ISUP

   For interoperability reasons the Q.850 Cause Value of a Release shall
   be mapped to the Reason Header.


6.  Security Considerations

   The presence of the Reason header in a response does not affect the
   treatment of the response.

   Including such a header by an untrusted entity could adulterate the
   reactions of the originating entities.  E.G. sending back a cause
   value "87" can cause an announcement within the PSTN/ISDN saying that
   the call was rejected due to the Closed User Group service.

   Therefore it is RECOMMENDED to include the Reason header information
   in Responses only by trusted entities as it is described within
   [RFC3325].






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7.  IANA Considerations

   This document describes the use of the Reason header field described
   within [RFC3326] .  No additional SIP elements are defined within
   this document.  Therefore, this document does not provide any action
   to IANA.


8.  Normative References

   [I-D.ietf-sipcore-199]
              Holmberg, C., "Response Code for Indication of Terminated
              Dialog", draft-ietf-sipcore-199-00 (work in progress),
              April 2009.

   [Q.850]    "Usage of cause and location in the Digital Subscriber
              Signalling System No. 1 and the Signalling System No. 7
              ISDN User Part [ITU-T Recommendation Q.850]",
              ITU Recommendation Q.850, April 1998.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC3325]  Jennings, C., Peterson, J., and M. Watson, "Private
              Extensions to the Session Initiation Protocol (SIP) for
              Asserted Identity within Trusted Networks", RFC 3325,
              November 2002.

   [RFC3326]  Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
              Header Field for the Session Initiation Protocol (SIP)",
              RFC 3326, December 2002.

   [draft-jesske-dispatch-requirements-reason-in-responses-00]
              Jesske, R. and L. Liess, "Requirements for the use of the
              Reason header filed in Session Initiation Protocol (SIP)
              responses]",  , March 2010.










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Authors' Addresses

   Roland Jesske
   Deutsche Telekom
   Heinrich-Hertz-Strasse 3-7
   Darmstadt,   64307
   Germany

   Phone: +4961516282766
   Email: r.jesske@telekom.de


   Laura Liess
   Deutsche Telekom
   Heinrich-Hertz-Strasse 3-7
   Darmstadt,   64307
   Germany

   Phone: +4961516282761
   Email: Laura.Liess@telekom.de































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