The Diameter Capabilities Update Application
RFC 6737

Internet Engineering Task Force (IETF)                           K. Jiao
Request for Comments: 6737                                        Huawei
Category: Standards Track                                        G. Zorn
ISSN: 2070-1721                                              Network Zen
                                                            October 2012

              The Diameter Capabilities Update Application

Abstract

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

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc6737.

Copyright Notice

   Copyright (c) 2012 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
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   described in the Simplified BSD License.

Jiao & Zorn                  Standards Track                    [Page 1]
RFC 6737              Diameter Capabilities Update          October 2012

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Specification of Requirements . . . . . . . . . . . . . . . . . 2
   3.  Diameter Protocol Considerations  . . . . . . . . . . . . . . . 3
   4.  Capabilities Update . . . . . . . . . . . . . . . . . . . . . . 3
     4.1.  Command Code Values . . . . . . . . . . . . . . . . . . . . 4
       4.1.1.  Capabilities-Update-Request . . . . . . . . . . . . . . 4
       4.1.2.  Capabilities-Update-Answer  . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
     6.1.  Application Identifier  . . . . . . . . . . . . . . . . . . 5
     6.2.  Command Codes . . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 6

1.  Introduction

   Capabilities exchange is an important component of the Diameter base
   protocol [RFC6733], 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 a 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 a subset of Diameter peer capabilities over an
   existing connection.  Because the Capabilities Update application
   specified herein operates over an existing transport connection,
   modification of certain capabilities is prohibited.  Specifically,
   modifying 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.

2.  Specification of Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this