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Versions: (draft-zorn-dime-capablities-update) 00 01 02 03 04 05 06 07 RFC 6737

Network Working Group                                            K. Jiao
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 G. Zorn
Expires: June 4, 2010                                        Network Zen
                                                        December 1, 2009


              The Diameter Capabilities Update Application
                 draft-ietf-dime-capablities-update-01

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.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
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   This Internet-Draft will expire on June 4, 2010.

Copyright Notice

   Copyright (c) 2009 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



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   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
   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 BSD License.


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.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
     6.1.  Application Identifier  . . . . . . . . . . . . . . . . . . 6
     6.2.  Command Codes . . . . . . . . . . . . . . . . . . . . . . . 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 dime Working Group of
   the IETF (dime@ietf.org).


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 RFC 2119 [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 MUST advertise support by
   including the value <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



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   has an open transport connection and have also advertised support for
   the Capabilities Update application using the Capabilities-Update-
   Request message Section 4.1.1.  This message allows the update of a
   peer's 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 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) Section 4.1.2 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 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.

   Even though the CUR/CUA messages cannot be proxied, it is still
   possible for an upstream agent to receive a message for which there
   are no peers available to handle the application that corresponds to
   the Command-Code.  This could happen if, for example, the peers are
   too busy or down.  In such instances, the 'E' bit MUST be 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 [RFC4960], 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.  Security Considerations

   The security considerations applicable to the Diameter Base Protocol
   [RFC3588] are also applicable to this document.


6.  IANA Considerations

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

6.1.  Application Identifier

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

6.2.  Command Codes

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


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

   [RFC4960]  Stewart, R., "Stream Control Transmission Protocol",
              RFC 4960, September 2007.













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Authors' Addresses

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

   Phone: +86 755 2878-6690
   Email: kangjiao@huawei.com


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

   Email: gwz@net-zen.net































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