unsolicited reauthentication and/or reauthorization request (e.g.,
Re-Auth-Request (RAR) message [BASE]) to the NAS. Upon receipt of
such a message, the NAS MUST respond to the request with a Re-Auth-
Answer (RAA) message [BASE].
If the RAR properly identifies an active session, the NAS will
initiate a new local reauthentication or authorization sequence as
indicated by the Re-Auth-Request-Type value. This will cause the NAS
to send a new AAR message using the existing Session-Id. The server
will respond with an AAA message to specify the new service
parameters.
If accounting is active, every change of authentication or
authorization SHOULD generate an accounting message. If the NAS
service is a continuation of the prior user context, then an
Accounting-Record-Type of INTERIM_RECORD indicating the new session
attributes and cumulative status would be appropriate. If a new user
or a significant change in authorization is detected by the NAS, then
the service may send two messages of the types STOP_RECORD and
START_RECORD. Accounting may change the subsession identifiers
(Acct-Session-ID, or Acct-Sub-Session-Id) to indicate such sub-
sessions. A service may also use a different Session-Id value for
accounting (see [BASE] section 9.6).
However, the Diameter Session-ID AVP value used for the initial
authorization exchange MUST be used to generate an STR message when
the session context is terminated.
2.3. Diameter Session Termination
When a NAS receives an indication that a user’s session is being
disconnected by the client (e.g., LCP Terminate is received) or an
administrative command, the NAS MUST issue a Session-Termination-
Request (STR) [BASE] to its Diameter Server. This will ensure that
any resources maintained on the servers are freed appropriately.
Furthermore, a NAS that receives an Abort-Session-Request (ASR)
[BASE] MUST issue an ASA if the session identified is active and
disconnect the PPP (or tunneling) session.
If accounting is active, an Accounting STOP_RECORD message [BASE]
MUST be sent upon termination of the session context.
More information on Diameter Session Termination is included in
[BASE] sections 8.4 and 8.5.
3. NAS Messages
This section defines the Diameter message Command-Code [BASE] values
that MUST be supported by all Diameter implementations conforming to
this specification. The Command Codes are as follows:
Command-Name Abbrev. Code Reference
-------------------------------------------------------
AA-Request AAR 265 3.1
AA-Answer AAA 265 3.2
Re-Auth-Request RAR 258 3.3
Re-Auth-Answer RAA 258 3.4
Session-Termination-Request STR 275 3.5
Session-Termination-Answer STA 275 3.6
Abort-Session-Request ASR 274 3.7
Abort-Session-Answer ASA 274 3.8
Accounting-Request ACR 271 3.9
Accounting-Answer ACA 271 3.10
3.1. AA-Request (AAR) Command
The AA-Request (AAR), which is indicated by setting the Command-Code
field to 265 and the ’R’ bit in the Command Flags field, is used to
request authentication and/or authorization for a given NAS user.
The type of request is identified through the Auth-Request-Type AVP
[BASE]. The recommended value for most RADIUS interoperabily
situations is AUTHORIZE_AUTHENTICATE.
If Authentication is requested, the User-Name attribute SHOULD be
present, as well as any additional authentication AVPs that would
carry the password information. A request for authorization SHOULD
only include the information from which the authorization will be
performed, such as the User-Name, Called-Station-Id, or Calling-
Station-Id AVPs. All requests SHOULD contain AVPs uniquely
identifying the source of the call, such as Origin-Host and NAS-Port.
Certain networks MAY use different AVPs for authorization purposes.
A request for authorization will include some AVPs defined in section
6.
It is possible for a single session to be authorized first and then
for an authentication request to follow.
This AA-Request message MAY be the result of a multi-round
authentication exchange, which occurs when the AA-Answer message is
received with the Result-Code AVP set to DIAMETER_MULTI_ROUND_AUTH.
A subsequent AAR message SHOULD be sent, with the User-Password AVP
that includes the user’s response to the prompt, and MUST include any
State AVPs that were present in the AAA message.
Message Format
<AA-Request> ::= < Diameter Header: 265, REQ, PXY >
< Session-Id >
{ Auth-Application-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Auth-Request-Type }
[ Destination-Host ]
[ NAS-Identifier ]
[ NAS-IP-Address ]
[ NAS-IPv6-Address ]
[ NAS-Port ]
[ NAS-Port-Id ]
[ NAS-Port-Type ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
[ Port-Limit ]
[ User-Name ]
[ User-Password ]
[ Service-Type ]
[ State ]
[ Authorization-Lifetime ]
[ Auth-Grace-Period ]
[ Auth-Session-State ]
[ Callback-Number ]
[ Called-Station-Id ]
[ Calling-Station-Id ]
[ Originating-Line-Info ]
[ Connect-Info ]
[ CHAP-Auth ]
[ CHAP-Challenge ]
* [ Framed-Compression ]
[ Framed-Interface-Id ]
[ Framed-IP-Address ]
* [ Framed-IPv6-Prefix ]
[ Framed-IP-Netmask ]
[ Framed-MTU ]
[ Framed-Protocol ]
[ ARAP-Password ]
[ ARAP-Security ]
* [ ARAP-Security-Data ]
* [ Login-IP-Host ]
* [ Login-IPv6-Host ]
[ Login-LAT-Group ]
[ Login-LAT-Node ]
[ Login-LAT-Port ]
[ Login-LAT-Service ]
* [ Tunneling ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
3.2. AA-Answer (AAA) Command
The AA-Answer (AAA) message is indicated by setting the Command-Code
field to 265 and clearing the ’R’ bit in the Command Flags field. It
is sent in response to the AA-Request (AAR) message. If
authorization was requested, a successful response will include the
authorization AVPs appropriate for the service being provided, as
defined in section 6.
For authentication exchanges requiring more than a single round trip,
the server MUST set the Result-Code AVP to DIAMETER_MULTI_ROUND_AUTH.
An AAA message with this result code MAY include one Reply-Message or
more and MAY include zero or one State AVPs.
If the Reply-Message AVP was present, the network access server
SHOULD send the text to the user’s client to display to the user,
instructing the client to prompt the user for a response. For
example, this capability can be achieved in PPP via PAP. If the
access client is unable to prompt the user for a new response, it
MUST treat the AA-Answer (AAA) with the Reply-Message AVP as an error
and deny access.
Message Format
<AA-Answer> ::= < Diameter Header: 265, PXY >
< Session-Id >
{ Auth-Application-Id }
{ Auth-Request-Type }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
[ Service-Type ]
* [ Class ]
* [ Configuration-Token ]
[ Acct-Interim-Interval ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
[ Idle-Timeout ]
[ Authorization-Lifetime ]
[ Auth-Grace-Period ]
[ Auth-Session-State ]
[ Re-Auth-Request-Type ]
[ Multi-Round-Time-Out ]
[ Session-Timeout ]
[ State ]
* [ Reply-Message ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
* [ Filter-Id ]
[ Password-Retry ]
[ Port-Limit ]
[ Prompt ]
[ ARAP-Challenge-Response ]
[ ARAP-Features ]
[ ARAP-Security ]
* [ ARAP-Security-Data ]
[ ARAP-Zone-Access ]
[ Callback-Id ]
[ Callback-Number ]
[ Framed-Appletalk-Link ]
* [ Framed-Appletalk-Network ]
[ Framed-Appletalk-Zone ]
* [ Framed-Compression ]
[ Framed-Interface-Id ]
[ Framed-IP-Address ]
* [ Framed-IPv6-Prefix ]
[ Framed-IPv6-Pool ]
* [ Framed-IPv6-Route ]
[ Framed-IP-Netmask ]
* [ Framed-Route ]
[ Framed-Pool ]
[ Framed-IPX-Network ]
[ Framed-MTU ]
[ Framed-Protocol ]
[ Framed-Routing ]
* [ Login-IP-Host ]
* [ Login-IPv6-Host ]
[ Login-LAT-Group ]
[ Login-LAT-Node ]
[ Login-LAT-Port ]
[ Login-LAT-Service ]
[ Login-Service ]
[ Login-TCP-Port ]
* [ NAS-Filter-Rule ]
* [ QoS-Filter-Rule ]
* [ Tunneling ]
* [ Redirect-Host ]
[ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ AVP ]
3.3. Re-Auth-Request (RAR) Command
A Diameter server may initiate a re-authentication and/or re-
authorization service for a particular session by issuing a Re-Auth-
Request (RAR) message [BASE].
For example, for pre-paid services, the Diameter server that
originally authorized a session may need some confirmation that the
user is still using the services.
If a NAS receives an RAR message with Session-Id equal to a currently
active session and a Re-Auth-Type that includes authentication, it
MUST initiate a re-authentication toward the user, if the service
supports this particular feature.
Message Format
<RA-Request> ::= < Diameter Header: 258, REQ, PXY >
< Session-Id >
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Destination-Host }
{ Auth-Application-Id }
{ Re-Auth-Request-Type }
[ User-Name ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
[ NAS-Identifier ]
[ NAS-IP-Address ]
[ NAS-IPv6-Address ]
[ NAS-Port ]
[ NAS-Port-Id ]
[ NAS-Port-Type ]
[ Service-Type ]
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Framed-Interface-Id ]
[ Called-Station-Id ]
[ Calling-Station-Id ]
[ Originating-Line-Info ]
[ Acct-Session-Id ]
[ Acct-Multi-Session-Id ]
[ State ]
* [ Class ]
[ Reply-Message ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
3.4. Re-Auth-Answer (RAA) Command
The Re-Auth-Answer (RAA) message [BASE] is sent in response to the
RAR. The Result-Code AVP MUST be present and indicates the
disposition of the request.
A successful RAA transaction MUST be followed by an AAR message.
Message Format
<RA-Answer> ::= < Diameter Header: 258, PXY >
< Session-Id >
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
* [ Redirected-Host ]
[ Redirected-Host-Usage ]
[ Redirected-Host-Cache-Time ]
[ Service-Type ]
* [ Configuration-Token ]
[ Idle-Timeout ]
[ Authorization-Lifetime ]
[ Auth-Grace-Period ]
[ Re-Auth-Request-Type ]
[ State ]
* [ Class ]
* [ Reply-Message ]
[ Prompt ]
* [ Proxy-Info ]
* [ AVP ]
3.5. Session-Termination-Request (STR) Command
The Session-Termination-Request (STR) message [BASE] is sent by the
NAS to inform the Diameter Server that an authenticated and/or
authorized session is being terminated.
Message Format
<ST-Request> ::= < Diameter Header: 275, REQ, PXY >
< Session-Id >
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Auth-Application-Id }
{ Termination-Cause }
[ User-Name ]
[ Destination-Host ]
* [ Class ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
3.6. Session-Termination-Answer (STA) Command
The Session-Termination-Answer (STA) message [BASE] is sent by the
Diameter Server to acknowledge the notification that the session has
been terminated. The Result-Code AVP MUST be present and MAY contain
an indication that an error occurred while the STR was being
serviced.
Upon sending or receiving the STA, the Diameter Server MUST release
all resources for the session indicated by the Session-Id AVP. Any
intermediate server in the Proxy-Chain MAY also release any
resources, if necessary.
Message Format
<ST-Answer> ::= < Diameter Header: 275, PXY >
< Session-Id >
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ User-Name ]
* [ Class ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
[ Origin-AAA-Protocol ]
[ Origin-State-Id ]
* [ Redirect-Host ]
[ Redirect-Host-Usase ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ AVP ]