Network Working Group K. Jiao
Internet-Draft Huawei
Intended status: Standards Track G. Zorn
Expires: April 27, 2011 Network Zen
October 24, 2010
The Diameter Capabilities Update Application
draft-ietf-dime-capablities-update-07
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 Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 27, 2011.
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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 [I-D.ietf-dime-rfc3588bis], 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.
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-Request (CER) and Capabilities-Exchange-Answer
(CEA) commands [I-D.ietf-dime-rfc3588bis].
4. Capabilities Update
When the capabilities of a Diameter node conforming to this
specification change, it 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
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Capabilities-Update-Request (CUR) message (Section 4.1.1). 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 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 CUR 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 [I-D.ietf-dime-rfc3588bis], 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
[I-D.ietf-dime-rfc3588bis], Section 2.4) 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.
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 [I-D.ietf-dime-rfc3588bis] values
that MUST be supported by all Diameter implementations conforming to
this specification. The following Command Codes are defined (using
modified ABNF [I-D.ietf-dime-rfc3588bis]) 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 <CUCC> 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
[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: <CUCC>, 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
<CUCC> and the Command Flags' 'R' bit cleared, is sent in response to
a CUR message.
Message Format
<CUA> ::= < Diameter Header: <CUCC> >
{ 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
[I-D.ietf-dime-rfc3588bis] 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 [I-D.ietf-dime-rfc3588bis]. See Section 3 for
the assignment of the namespace in this specification.
6.2. Command Codes
This specification assigns the value <CUCC> from the Command Codes
namespace [I-D.ietf-dime-rfc3588bis]. 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, Lionel
Morand, Dan Romascanu, Dan Harkins and Ravi for helpful review and
discussion.
9. References
9.1. Normative References
[I-D.ietf-dime-rfc3588bis]
Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", draft-ietf-dime-rfc3588bis-25
(work in progress), September 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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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: [email protected]
Glen Zorn
Network Zen
227/358 Thanon Sanphawut
Bang Na, Bangkok 10260
Thailand
Phone: +66 (0) 87-040-4617
Email: [email protected]
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