Network Working Group K. Jiao
Internet-Draft Huawei
Intended status: Standards Track G. Zorn
Expires: August 30, 2010 Network Zen
February 26, 2010
The Diameter Capabilities Update Application
draft-ietf-dime-capablities-update-02
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
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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. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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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 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.
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
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specification change, it SHOULD notify all of the nodes with which it
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.).
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 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. Contributors
This document is based upon work done by Tina Tsou.
8. Acknowledgements
Thanks to Sebastien Decugis, Niklas Neumann, Subash Comerica and Ravi
for helpful discussion.
9. References
9.1. 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.
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9.2. Informative References
[RFC4960] Stewart, R., "Stream Control Transmission Protocol",
RFC 4960, September 2007.
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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