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Versions: 00 01 draft-ietf-dime-capablities-update

Network Working Group                                            G. Zorn
Internet-Draft                                               Network Zen
Intended status: Standards Track                                 K. Jiao
Expires: October 15, 2009                            Huawei Technologies
                                                          April 13, 2009


              The Diameter Capabilities Update Application
               draft-zorn-dime-capablities-update-01.txt

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   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Abstract

   This document defines a new Diameter application and associated
   command codes.  The Capabilities Update application is intended to
   allow the dynamic update of Diameter peer capabilities while the
   peer-to-peer connection is in the open state.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Specification of Requirements . . . . . . . . . . . . . . . . . 3
   3.  Diameter Protocol Considerations  . . . . . . . . . . . . . . . 3
   4.  Capabilities Update . . . . . . . . . . . . . . . . . . . . . . 3
     4.1.  Command-Code Values . . . . . . . . . . . . . . . . . . . . 4
       4.1.1.  Capabilities-Update-Request . . . . . . . . . . . . . . 5
       4.1.2.  Capabilities-Update-Answer  . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
     5.1.  Application Identifier  . . . . . . . . . . . . . . . . . . 6
     5.2.  Command Codes . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6




















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1.  Introduction

   Capabilities exchange is an important component of the Diameter Base
   Protocol [RFC3588], allowing peers to exchange identities and
   Diameter capabilities (protocol version number, supported Diameter
   applications, security mechanisms, etc.).  As defined in RFC 3588,
   however, the capabilities exchange process takes place only once, at
   the inception of a transport connection between a given pair of
   peers.  Therefore, if a peer's capabilities change (due to software
   update, for example), the existing connection(s) must be torn down
   (along with all of the associated user sessions) and restarted before
   the modified capabilities can be advertised.

   This document defines a new Diameter application intended to allow
   the dynamic update of Diameter peer capabilities over an existing
   connection.  Because the Capabilities Update application specified
   here operates over an existing transport connection, modification of
   the security mechanism in use is not allowed; if the security method
   used between a pair of peers is changed the affected connection MUST
   be restarted.

   Discussion of this draft may be directed to the authors.


2.  Specification of Requirements

   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].


3.  Diameter Protocol Considerations

   This section details the relationship of the Diameter Capabilities
   Update application to the Diameter Base Protocol.

   This document specifies Diameter Application-ID <TBD1>.  Diameter
   nodes conforming to this specification MAY advertise support by
   including the value of <TBD1> in the Auth-Application-Id of the
   Capabilities-Exchange-Req and Capabilities-Exchange-Answer commands
   [RFC3588].


4.  Capabilities Update

   When the capabilities of a Diameter node conforming to this
   specification change, it SHOULD notify all of the nodes with which it
   has an open transport connection using the Capabilities-Update-Req



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   message (Section 4.1.1).  This message allows the update of a peer's
   identity and its capabilities (protocol version number, supported
   Diameter applications, etc.).

   The receiver only issues commands to its peers that have advertised
   support for the Diameter application that defines the command.  A
   Diameter node MUST cache the supported applications in order to
   ensure that unrecognized commands and/or AVPs are not unnecessarily
   sent to a peer.

   The receiver of the Capabilities-Update-Request (CUR) MUST determine
   common applications by computing the intersection of its own set of
   supported Application Id against all of the application identifier
   AVPs (Auth-Application-Id, Acct-Application-Id and Vendor-Specific-
   Application-Id) present in the CUR.  The value of the Vendor-Id AVP
   in the Vendor-Specific-Application-Id MUST NOT be used during
   computation.

   If the receiver of a Capabilities-Update-Req (CUR) message does not
   have any applications in common with the sender then it MUST return a
   Capabilities-Update-Answer (CUA) with the Result-Code AVP set to
   DIAMETER_NO_COMMON_APPLICATION, and SHOULD disconnect the transport
   layer connection; however, if active sessions are using the
   connection, peers MAY delay disconnection until the sessions can be
   redirected or gracefully terminated.  Note that receiving a CUR or
   CUA from a peer advertising itself as a Relay (see [RFC3588], Section
   2.4) MUST be interpreted as having common applications with the peer.

   The CUR and CUA messages MUST NOT be proxied, redirected or relayed.

   Since the CUR/CUA messages cannot be proxied, it is still possible
   that an upstream agent receives a message for which it has no
   available peers to handle the application that corresponds to the
   Command-Code.  In such instances, the 'E' bit is set in the answer
   message with the Result-Code AVP set to DIAMETER_UNABLE_TO_DELIVER to
   inform the downstream peer to take action (e.g., re-routing requests
   to an alternate peer).

4.1.  Command-Code Values

   This section defines Command-Code [RFC3588] values that MUST be
   supported by all Diameter implementations conforming to this
   specification.  The following Command Codes are defined in this
   document: Capabilities-Update-Request (CUR)Section 4.1.1 and
   Capabilities-Update-Answer (CUA) Section 4.1.2.






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4.1.1.  Capabilities-Update-Request

   The Capabilities-Update-Request (CUR), indicated by the Command-Code
   set to <TBD2> and the Command Flags' 'R' bit set, is sent to update
   local capabilities.  Upon detection of a transport failure, this
   message MUST NOT be sent to an alternate peer.

   When Diameter is run over SCTP [RFC2960], which allows connections to
   span multiple interfaces and multiple IP addresses, the Capabilities-
   Update-Request message MUST contain one Host-IP-Address AVP for each
   potential IP address that may be locally used when transmitting
   Diameter messages.

         Message Format

            <CUR> ::= < Diameter Header: TBD2, REQ >
                      { Origin-Host }
                      { Origin-Realm }
                   1* { Host-IP-Address }
                      { Vendor-Id }
                      { Product-Name }
                      [ Origin-State-Id ]
                    * [ Supported-Vendor-Id ]
                    * [ Auth-Application-Id ]
                    * [ Acct-Application-Id ]
                    * [ Vendor-Specific-Application-Id ]
                      [ Firmware-Revision ]
                    * [ AVP ]

4.1.2.  Capabilities-Update-Answer

   The Capabilities-Update-Answer indicated by the Command-Code set to
   <TBD3> and the Command Flags' 'R' bit set, is sent in response to a
   CUR message.

         Message Format

            <CUA> ::= < Diameter Header: TBD3 >
                      { Origin-Host }
                      { Origin-Realm }
                      { Result-Code }
                      [ Error-Message ]
                    * [ AVP ]








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5.  IANA Considerations

   This section explains the criteria to be used by the IANA for
   assignment of numbers within namespaces used within this document.

5.1.  Application Identifier

   This specification assigns the value <TBD1> from the Application
   Identifiers namespace defined in RFC 3588.  See section Section 3 for
   the assignment of the namespace in this specification.

5.2.  Command Codes

   This specification assigns the values <TBD2> and <TBD3> from the
   Command Codes namespace defined in RFC 3588.  See section Section 4.1
   for the assignment of the namespace in this specification.


6.  Security Considerations

   This document does not introduce any new vulnerabilities into the
   Diameter protocol.


7.  References

7.1.  Normative References

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

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

7.2.  Informative References

   [RFC2960]  Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
              Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
              Zhang, L., and V. Paxson, "Stream Control Transmission
              Protocol", RFC 2960, October 2000.











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Authors' Addresses

   Glen Zorn
   Network Zen
   1310 East Thomas Street
   #306
   Seattle, Washington  98102
   USA

   Phone: +1 (206) 377-9035
   Email: gwz@net-zen.net


   Jiao Kang
   Huawei Technologies
   Section B1, Huawei Industrial Base
   Bantian, Longgang District
   Shenzhen  518129
   P.R. China

   Phone: +86 755 28786690
   Email: kangjiao@huawei.com





























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