| DIME | M. Jones |
| Internet-Draft | Bridgewater Systems |
| Intended status: Informational | October 24, 2011 |
| Expires: April 26, 2012 |
Diameter Group Signaling
draft-jones-diameter-group-signaling-00.txt
In large network deployments, a single Diameter peer can support over a million concurrent Diameter sessions. Recent use cases have revealed the need for Diameter peers to apply the same operation to a large group of Diameter sessions concurrently. The Diameter base protocol commands operate on a single session so these use cases could result in many thousands of command exchanges in order to enforce the same operation on each session in the group. In order to reduce signaling, it would be desirable to enable bulk operations on all (or part of) the sessions managed by a Diameter peer using a single or a few command exchanges. This document specifies the Diameter protocol extensions to achieve this signaling optimization.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on April 26, 2012.
Copyright (c) 2011 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 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 Simplified BSD License.
In large network deployments, a single Diameter peer can support over a million concurrent Diameter sessions. Recent use cases have revealed the need for Diameter peers to apply the same operation to a large group of Diameter sessions concurrently. For example, a policy decision point may need to modify the authorized quality of service for all active users having the same type of subscription. The Diameter base protocol commands operate on a single session so these use cases could result in many thousands of command exchanges in order to enforce the same operation on each session in the group. In order to reduce signaling, it would be desirable to enable bulk operations on all (or part of) the sessions managed by a Diameter peer using a single or a few command exchanges.
This document describes a mechanism for grouping Diameter sessions and performing re-authentication, re-authorization, termination and abortion of groups of sessions. This document does not define a new Diameter application. Instead it defines mechanisms, commands and AVPs that may be used by any Diameter application that requires management of groups of sessions.
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].
This document uses terminology defined [RFC3588].
Either Diameter peer may assign a session to a group. Diameter AAA applications typically assign client and server roles to the Diameter peers. In this document, a Diameter client is a node at the edge of the network that performs access control. A Diameter server is a node that performs authentication and/or authorization of the user.
To assign a session to a group at session initiation, a Diameter client sends a service specific auth request, e.g. NASREQ AAR [RFC4005], containing one or more client-assigned group identifiers. Assuming the user is successfully authenticated and/or authorized, the Diameter server responds with service-specific auth response, e.g. NASREQ AAA [RFC4005], containing both the client-assigned group identifiers and the server-assigned group identifiers.
Either Diameter peer may modify the group membership of an active Diameter session. A Diameter client MAY remove the group(s) assigned to the active session by the Diameter server and vice versa.
Editor's Note: It is FFS whether this document should define a default permission model limiting removal of a session from a group. For example, the server MUST NOT remove a session from a group assigned by the client.
To update the assigned groups mid-session, a Diameter client sends a service specific re-authorization request containing the updated list of group identifiers. Assuming the user is successfully authenticated and/or authorized, the Diameter server responds with a service-specific auth response containing the updated list of group identifiers received in the request.
To update the assigned groups mid-session, a Diameter server sends a Re-authorization Request (RAR) message requesting re-authorization and the client responds with a Re-authorization Answer (RAA) message. The Diameter client sends a service specific re-authorization request containing the current list of group identifiers and the Diameter server responds with a service-specific auth response containing the updated list of group identifiers.
Section 8.1 in [RFC3588] defines a set of finite state machines, representing the life cycle of Diameter sessions, and which MUST be observed by all Diameter implementations that make use of the authentication and/or authorization portion of a Diameter application. This section defines the additional state transitions related to the processing of the new commands which may impact multiple sessions.
The group membership is session state and therefore only those state machines from [RFC3588] in which the server is maintaining session state are relevant in this document. As in [RFC3588], the term Service-Specific below refers to a message defined in a Diameter application (e.g., Mobile IPv4, NASREQ).
The following state machine is observed by a client when state is maintained on the server. State transitions which are unmodified from [RFC3588] are not repeated here.
CLIENT, STATEFUL
State Event Action New State
---------------------------------------------------------------
Idle Client or Device Requests Send Pending
access service
specific
auth req
optionally
including
groups
Open BASR received with Send BASA Discon
Session-Group-Action with
= ALL_GROUPS, Result-Code
session is assigned to = SUCCESS,
received group(s) and Send BSTR.
client will comply with
request to end the session
Open BASR received with Send BASA Discon
Session-Group-Action with
= PER_GROUPS, Result-Code
session is assigned to = SUCCESS,
received group(s) and Send BSTR
client will comply with per group
request to end the session
Open BASR received with Send BASA Discon
Session-Group-Action with
= PER_SESSION, Result-Code
session is assigned to = SUCCESS,
received group(s) and Send STR
client will comply with per session
request to end the session
Open BASR received, Send BASA Open
client will not comply with with
request to end all session Result-Code
in received group(s) != SUCCESS
Discon BSTA Received Discon. Idle
user/device
Open BRAR received with Send BRAA, Pending
Session-Group-Action Send
= ALL_GROUPS, service
session is assigned to specific
received group(s) and group
client will perform re-auth req
subsequent re-auth
Open BRAR received with Send BRAA, Pending
Session-Group-Action Send
= PER_GROUP, service
session is assigned to specific
received group(s) and group
client will perform re-auth req
subsequent re-auth per group
Open BRAR received with Send BRAA, Pending
Session-Group-Action Send
= PER_SESSION, service
session is assigned to specific
received group(s) and re-auth req
client will perform per session
subsequent re-auth
Open BRAR received and client will Send BRAA Idle
not perform subsequent with
re-auth Result-Code
!= SUCCESS,
Discon.
user/device
Pending Successful service-specific Provide Open
group re-authorization answer service
received.
Pending Failed service-specific Discon. Idle
group re-authorization answer user/device
received.
The following state machine is observed by a server when it is maintaining state for the session. State transitions which are unmodified from [RFC3588] are not repeated here.
SERVER, STATEFUL
State Event Action New State
---------------------------------------------------------------
Idle Service-specific authorization Send Open
request received, and user successful
is authorized service
specific
answer
optionally
including
groups
Open Server wants to terminate Send BASR Discon
group(s)
Discon BASA received Cleanup Idle
Any BSTR received Send BSTA, Idle
Cleanup
Open Server wants to reauth Send BRAR Pending
group(s)
Pending BRAA received with Result-Code Update Open
= SUCCESS session(s)
Pending BRAA received with Result-Code Cleanup Idle
!= SUCCESS session(s)
Open Service-specific group Send Open
re-authoization request successful
received and user is service
authorized specific
group
re-auth
answer
Open Service-specific group Send Idle
re-authorization request failed
received and user is service
not authorized specific
group
re-auth
answer,
cleanup
TODO: rules/restrictions governing group re-auth
TODO: rules/restrictions governing session group termination
TODO: rules/restrictions governing aborting groups of session
This specification extends the existing RAR, RAA, STR, STA, ASR and ASA command ABNFs.
The Group-Re-Auth-Request (GRAR), indicated by the Command-Code set to TBD and the message flags' 'R' bit set, may be sent by any server to the access device that is providing session service, to request that one or more groups of users be re-authenticated and/or re-authorized.
<GRAR> ::= < Diameter Header: TBD, REQ, PXY >
* { Session-Group-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Destination-Host }
{ Auth-Application-Id }
{ Re-Auth-Request-Type }
[ User-Name ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ Route-Record ]
[ Session-Group-Action ]
* [ AVP ]
The Group-Re-Auth-Answer (GRAA), indicated by the Command-Code set to TBD and the message flags' 'R' bit clear, is sent in response to the GRAR. The Result-Code AVP MUST be present, and indicates the disposition of the request.
[Editor's Note: Move these detailed behaviour requirements to earlier section?]
A successful GRAA message MUST be followed by an application-specific authentication and/or authorization message. The Group-Action AVP in the Group-Re-Auth-Request indicates whether a single exchange, per-group or per-session is required.
If the peer receiving the GRAR has no active sessions which are assigned to the groups listed in the Session-Group-Id AVPs, it MUST return a GRAA with the Result-Code set to TBD.
The Session-Group-Id AVPs in the GRAA indicate the groups for which the GRAR receiver has active sessions assigned to those groups.
<GRAA> ::= < Diameter Header: TBD, PXY >
* { Session-Group-Id }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
[ Origin-State-Id ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
* [ Redirect-Host ]
[ Redirect-Host-Usage ]
[ Redirect-Host-Cache-Time ]
* [ Proxy-Info ]
* [ AVP ]
The Group-Session-Termination-Request (GSTR), indicated by the Command-Code set to TBD and the Command Flags' 'R' bit set, is sent by the access device to inform the Diameter Server that one or more groups of authenticated and/or authorized sessions are being terminated.
<GSTR> ::= < Diameter Header: TBD, REQ, PXY >
* { Session-Group-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Auth-Application-Id }
{ Termination-Cause }
[ User-Name ]
[ Destination-Host ]
* [ Class ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
The Group-Session-Termination-Answer (GSTA), indicated by the Command-Code set to TBD and the message flags' 'R' bit clear, is sent by the Diameter Server to acknowledge the notification that one or more groups of session have been terminated. The Result-Code AVP MUST be present, and MAY contain an indication that an error occurred while servicing the GSTR.
Upon sending or receipt of the GSTA, the Diameter Server MUST release all resources for all sessions belonging to the groups indicated by the Session-Group-Id AVP. Any intermediate server in the Proxy-Chain MAY also release any resources, if necessary.
<GSTA> ::= < Diameter Header: TBD, PXY >
* { Session-Group-Id }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
* [ Class ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
[ Origin-State-Id ]
* [ Redirect-Host ]
[ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ AVP ]
The Group-Abort-Session-Request (GASR), indicated by the Command-Code set to TBD and the message flags' 'R' bit set, may be sent by any server to the access device that is providing session service, to request that the sessions identified by the Session-Group-Id be stopped.
<GASR> ::= < Diameter Header: TBD, REQ, PXY >
* { Session-Group-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Destination-Host }
{ Auth-Application-Id }
[ User-Name ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ Route-Record ]
[ Group-Action ]
* [ AVP ]
The Group-Abort-Session-Answer (GASA), indicated by the Command-Code set to TBD and the message flags' 'R' bit clear, is sent in response to the GASR. The Result-Code AVP MUST be present, and indicates the disposition of the request.
If the sessions identified by Session-Group-Id in the GASR were successfully terminated, Result-Code is set to DIAMETER_SUCCESS. If the session is not currently active, Result-Code is set to DIAMETER_UNKNOWN_SESSION_ID. If the access device does not stop the session for any other reason, Result-Code is set to DIAMETER_UNABLE_TO_COMPLY.
[Editor's Note: Move these detailed behaviour requirements to earlier section.]
A successful GASA message MUST be followed by one or more STR or GSTR to the authorizing server. The Group-Action AVP in the Group-Abort-Session-Request indicates whether a GSTR per group of sessions, a GSTR per group or an STR per session is required.
If the peer receiving the GASR has no active sessions which are assigned the groups listed in the Session-Group-Id AVPs, it MUST return a GASA with the Result-Code set to TBD.
The Session-Group-Id AVPs in the GASA indicate the groups for which the GASR receiver has active sessions assigned to those groups.
<GASA> ::= < Diameter Header: TBD, PXY >
* { Session-Group-Id }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
[ Origin-State-Id ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
* [ Redirect-Host ]
[ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ AVP ]
+--------------------+
| AVP Flag rules |
+----+---+------+----+
AVP | | |SHOULD|MUST|
Attribute Name Code Value Type |MUST|MAY| NOT | NOT|
+---------------------------------------+----+---+------+----+
|Session-Group-Id TBD OctetString | | P | | V |
|Session-Group-Action TBD Enumerated | | P | | V |
+---------------------------------------+----+---+------+----+
The Session-Group-Action AVP (AVP Code TBD) is of type Enumerated and specifies how the peer SHOULD issue follow up exchanges in response to a command which impacts mulitple sessions. The following values are supported:
This section defines new Result-Code [RFC3588] values that MUST be supported by all Diameter implementations that conform to this specification.
[Editor's Note: Group specific error values may need to be added here.]
This section contains the namespaces that have either been created in this specification or had their values assigned to existing namespaces managed by IANA.
This specification requires IANA to register the following new Commands from the Command Code namespace defined in [RFC3588]. Section 4.2.
The commands are defined in
This specification requires IANA to register the following new AVPs from the AVP Code namespace defined in [RFC3588]. Section 5.
The AVPs are defined in
TODO
| [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. |
| [RFC4005] | Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter Network Access Server Application", RFC 4005, August 2005. |