6737
PROPOSED STANDARD
The Diameter Capabilities Update Application
Authors: K. Jiao, G. Zorn
Date: October 2012
Area: ops
Working Group: dime
Stream: IETF
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. [STANDARDS-TRACK]
RFC 6737
PROPOSED STANDARD
Internet Engineering Task Force (IETF) K. Jiao
Request for Comments: 6737 Huawei
Category: Standards Track G. Zorn
ISSN: 2070-1721 Network Zen
October 2012
<span class="h1">The Diameter Capabilities Update Application</span>
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 <a href="./rfc5741#section-2">Section 2 of RFC 5741</a>.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
<a href="https://www.rfc-editor.org/info/rfc6737">http://www.rfc-editor.org/info/rfc6737</a>.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
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described in the Simplified BSD License.
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Table of Contents
<a href="#section-1">1</a>. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-2">2</a>. Specification of Requirements . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-3">3</a>. Diameter Protocol Considerations . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-4">4</a>. Capabilities Update . . . . . . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-4.1">4.1</a>. Command Code Values . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-4.1.1">4.1.1</a>. Capabilities-Update-Request . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-4.1.2">4.1.2</a>. Capabilities-Update-Answer . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-5">5</a>. Security Considerations . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-6">6</a>. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-6.1">6.1</a>. Application Identifier . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-6.2">6.2</a>. Command Codes . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-7">7</a>. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-8">8</a>. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-9">9</a>. References . . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<a href="#section-9.1">9.1</a>. Normative References . . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<a href="#section-9.2">9.2</a>. Informative References . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
Capabilities exchange is an important component of the Diameter base
protocol [<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>], allowing peers to exchange identities and
Diameter capabilities (protocol version number, supported Diameter
applications, security mechanisms, etc.). As defined in <a href="./rfc3588">RFC 3588</a>,
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.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Specification of Requirements</span>
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 <a href="./rfc2119">RFC 2119</a> [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
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<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Diameter Protocol Considerations</span>
This section details the relationship of the Diameter Capabilities
Update application to the Diameter base protocol.
This document specifies Diameter Application-Id 10. Diameter nodes
conforming to this specification MUST advertise support by including
the value 10 in the Auth-Application-Id of the Capabilities-Exchange-
Request (CER) and Capabilities-Exchange-Answer (CEA) commands
[<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>].
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Capabilities Update</span>
When the capabilities of a Diameter node conforming to this
specification change, the node MUST notify all of the nodes with
which it has an open transport connection and which have also
advertised support for the Capabilities Update application using the
Capabilities-Update-Request (CUR) message (<a href="#section-4.1.1">Section 4.1.1</a>). This
message allows the update of a peer's capabilities (supported
Diameter applications, etc.).
A Diameter node only issues a given command to those 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 Attribute-Value
Pairs (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
Ids against all of the Application-Id 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 CUR does not have any applications in common
with the sender, then it MUST return a Capabilities-Update-Answer
(CUA) (<a href="#section-4.1.2">Section 4.1.2</a>) with the Result-Code AVP set to
DIAMETER_NO_COMMON_APPLICATION [<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>], and it 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
<a href="./rfc6733#section-2.4">[RFC6733], Section 2.4</a>) MUST be interpreted as having common
applications with the peer.
As for CER/CEA messages, the CUR and CUA messages MUST NOT be
proxied, redirected, or relayed.
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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).
<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Command Code Values</span>
This section defines Command Code [<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>] 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, <a href="#section-4.1.1">Section 4.1.1</a>), and
Capabilities-Update-Answer (CUA, <a href="#section-4.1.2">Section 4.1.2</a>). The Diameter
Command Code Format (CCF) (<a href="./rfc6733#section-3.2">[RFC6733], Section 3.2</a>) is used in the
definitions.
<span class="h4"><a class="selflink" id="section-4.1.1" href="#section-4.1.1">4.1.1</a>. Capabilities-Update-Request</span>
The Capabilities-Update-Request (CUR), indicated by the Command Code
set to 328 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 the Stream Control Transmission Protocol
(SCTP) [<a href="./rfc4960" title=""Stream Control Transmission Protocol"">RFC4960</a>], 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: 328, 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 ]
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<span class="h4"><a class="selflink" id="section-4.1.2" href="#section-4.1.2">4.1.2</a>. Capabilities-Update-Answer</span>
The Capabilities-Update-Answer, indicated by the Command Code set to
328 and the Command Flags' 'R' bit cleared, is sent in response to a
CUR message.
Message Format
<CUA> ::= < Diameter Header: 328 >
{ Origin-Host }
{ Origin-Realm }
{ Result-Code }
[ Error-Message ]
* [ AVP ]
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Security Considerations</span>
The security considerations applicable to the Diameter base protocol
[<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>] are also applicable to this document.
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. IANA Considerations</span>
This section explains the criteria to be used by the IANA for
assignment of numbers within namespaces used within this document.
<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. Application Identifier</span>
This specification assigns the value 10 (Diameter Capabilities
Update) from the Application Identifiers namespace [<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>]. See
<a href="#section-3">Section 3</a> for the assignment of the namespace in this specification.
<span class="h3"><a class="selflink" id="section-6.2" href="#section-6.2">6.2</a>. Command Codes</span>
This specification assigns the value 328 (Capabilities-Update-
Request/Capabilities-Update-Answer (CUR/CUA)) from the Command Codes
namespace [<a href="./rfc6733" title=""Diameter Base Protocol"">RFC6733</a>]. See <a href="#section-4.1">Section 4.1</a> for the assignment of the
namespace in this specification.
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Contributors</span>
This document is based upon work done by Tina Tsou.
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. Acknowledgements</span>
Thanks to Sebastien Decugis, Niklas Neumann, Subash Comerica, Lionel
Morand, Dan Romascanu, Dan Harkins, and Ravi for helpful review and
discussion.
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<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>. References</span>
<span class="h3"><a class="selflink" id="section-9.1" href="#section-9.1">9.1</a>. Normative References</span>
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC6733">RFC6733</a>] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", <a href="./rfc6733">RFC 6733</a>, October 2012.
<span class="h3"><a class="selflink" id="section-9.2" href="#section-9.2">9.2</a>. Informative References</span>
[<a id="ref-RFC4960">RFC4960</a>] Stewart, R., "Stream Control Transmission Protocol",
<a href="./rfc4960">RFC 4960</a>, September 2007.
Authors' Addresses
Jiao Kang
Huawei Technologies
Section F1, Huawei Industrial Base
Bantian, Longgang District
Shenzhen 518129
P.R. China
EMail: [email protected]
Glen Zorn
Network Zen
227/358 Thanon Sanphawut
Bang Na, Bangkok 10260
Thailand
Phone: +66 (0) 909-201060
EMail: [email protected]
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