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Contents
- Change of Authorization Support
- Finding Feature Information
- Information About CoA Support
- RADIUS Change-of-Authorization Support
- Session Identification
- CoA Activate Service Command
- CoA Deactivate Service Command
- CoA Bounce Host Port Command
- CoA Disable Host Port Command
- CoA Session Query Command
- CoA Session Reauthenticate Command
- CoA Session Terminate Command
- Additional References
- Feature Information for CoA Support
Change of Authorization Support
Session Aware Networking supports RADIUS change of authorization (CoA) commands for session query, reauthentication, and termination, port bounce and port shutdown, and service template activation and deactivation. This module provides information about the supported CoA commands for Session Aware Networking.
- Finding Feature Information
- Information About CoA Support
- Additional References
- Feature Information for CoA Support
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About CoA Support
RADIUS Change-of-Authorization Support
Cisco IOS software supports the RADIUS CoA extensions defined in RFC 5176 that are typically used in a push model to allow the dynamic reconfiguring of sessions from external AAA or policy servers. Per-session CoA requests are supported for session identification, session termination, host reauthentication, port shutdown, and port bounce. This model comprises one request (CoA-Request) and two possible response codes:
The request is initiated from a CoA client (typically a AAA or policy server) and directed to the device that acts as a listener.
The table below shows the RADIUS CoA commands and vendor-specific attributes (VSAs) supported by Session Aware Networking. All CoA commands must include the session identifier between the device and the CoA client.
Table 1 RADIUS CoA Commands Supported by Session Aware Networking CoA Command
Cisco VSA
Activate service
Cisco:Avpair=“subscriber:command=activate-service”
Cisco:Avpair=“subscriber:service-name=<service-name>”
Cisco:Avpair=“subscriber:precedence=<precedence-number>”
Cisco:Avpair=“subscriber:activation-mode=replace-all”
Deactivate service
Cisco:Avpair=“subscriber:command=deactivate-service”
Cisco:Avpair=“subscriber:service-name=<service-name>”
Bounce host port
Cisco:Avpair=“subscriber:command=bounce-host-port”
Disable host port
Cisco:Avpair=“subscriber:command=disable-host-port”
Session query
Cisco:Avpair=“subscriber:command=session-query”
Session reauthenticate
Cisco:Avpair=“subscriber:command=reauthenticate”
Cisco:Avpair=“subscriber:reauthenticate-type=last” or
Cisco:Avpair=“subscriber:reauthenticate-type=rerun”
Session terminate
This is a standard disconnect request and does not require a VSA.
Session Identification
For disconnect and CoA requests targeted at a particular session, the device locates the session based on one or more of the following attributes:
- Acct-Session-Id (IETF attribute #44)
- Audit-Session-Id (Cisco VSA)
- Calling-Station-Id (IETF attribute #31, which contains the host MAC address)
- Plain IP Address (IETF attribute #8)
If more than one session identification attribute is included in the message, all of the attributes must match the session or the device returns a Disconnect-NAK or CoA-NAK with the error code “Invalid Attribute Value.”
For CoA requests targeted at a particular enforcement policy, the device returns a CoA-NAK with the error code “Invalid Attribute Value” if any of the above session identification attributes are included in the message.
CoA Activate Service Command
The CoA activate service command can be used to activate a service template on a session. The AAA server sends the request in a standard CoA-Request message using the following VSAs:
Cisco:Avpair=“subscriber:command=activate-service”
Cisco:Avpair=“subscriber:service-name=<service-name>”
Cisco:Avpair=“subscriber:precedence=<precedence-number>”
Cisco:Avpair=“subscriber:activation-mode=replace-all”
Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the device cannot locate a session, it returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the device locates a session, it initiates an activate template operation for the hosting port and a CoA-ACK is returned. If activating the template fails, a CoA-NAK message is returned with the Error-Code attribute set to the appropriate message.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
CoA Deactivate Service Command
The CoA deactivate service command can be used to deactivate a service template on a session. The AAA server sends the request in a standard CoA-Request message using the following VSAs:
Cisco:Avpair=“subscriber:command=deactivate-service”
Cisco:Avpair=“subscriber:service-name=<service-name>”
Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the device cannot locate a session, it returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the device locates a session, it initiates a deactivate template operation for the hosting port and a CoA-ACK is returned. If deactivating the template fails, a CoA-NAK message is returned with the Error-Code attribute set to the appropriate message.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
CoA Bounce Host Port Command
The CoA bounce host port command terminates a session and bounces the port (initiates a link down event followed by a link up event). The AAA server sends the request in a standard CoA-Request message with the following VSA:
Cisco:Avpair=“subscriber:command=bounce-host-port”
Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the session cannot be located, the device returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the device disables the hosting port for a period of ten seconds, reenables it (port bounce), and returns a CoA-ACK.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
The CoA bounce port command is useful as a last resort when an endpoint needs to acquire a new IP address after a change in authorization and this is the only way to indicate to the endpoint to restart the DHCP process. This can occur when there is a VLAN change and the endpoint is a device, such as a printer, that does not have a mechanism to detect a change on this authentication port. This command can cause a link flap on an authentication port, which triggers DHCP renegotiation from one or more hosts connected to this port.
CoA Disable Host Port Command
The CoA disable host port command administratively shuts down the authentication port that is hosting a session, which terminates the session. The AAA server sends the request in a standard CoA-Request message with the following VSA:
Cisco:Avpair=“subscriber:command=disable-host-port”
Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the device cannot locate the session, it returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the device locates the session, it disables the hosting port and returns a CoA-ACK message.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
CoA Session Query Command
The CoA session query command requests service information about a subscriber session. The AAA server sends the request in a standard CoA-Request message containing the following VSA:
Cisco:Avpair=“subscriber:command=session-query”
Because this command is session-oriented, it must be accompanied by one or more of the session identification attributes described in the “Session Identification” section. If the device cannot locate a session, it returns a CoA-NAK message with the “Session Context Not Found” error-code attribute. If the device locates a session, it performs a session query operation on the session and returns a CoA-ACK message.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
CoA Session Reauthenticate Command
To initiate session authentication, the AAA server sends a standard CoA-Request message containing the following VSAs:
Cisco:Avpair=“subscriber:command=reauthenticate”
Cisco:Avpair=“subscriber:reauthenticate-type=<last | rerun>”
“reauthenticate-type” defines whether the CoA reauthentication request uses the authentication method that last succeeded on the session or whether the authentication process is completely rerun.
The following rules apply:
- “subscriber:command=reauthenticate” must be present to trigger a reauthentication.
- If “subscriber:reauthenticate-type” is not specified, the default behavior is to rerun the last successful authentication method for the session. If the method reauthenticates successfully, all old authorization data is replaced with the new reauthenticated authorization data.
- “subscriber:reauthenticate-type” is valid only when included with “subscriber:command=reauthenticate.” If it is included in another CoA command, the VSA will be silently ignored.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is resent from the client. If the device fails after returning a CoA-ACK message to the client but before the operation is complete, the operation is restarted on the new active device.
CoA Session Terminate Command
A CoA Disconnect-Request command terminates a session without disabling the host port. This command causes reinitialization of the authenticator state machine for the specified host, but does not restrict the host’s access to the network. If the session cannot be located, the device returns a Disconnect-NAK message with the “Session Context Not Found” error-code attribute. If the session is located, the device terminates the session. After the session has been completely removed, the device returns a Disconnect-ACK.
If the device fails before returning a CoA-ACK to the client, the process is repeated on the new active device when the request is re-sent from the client.
To restrict a host’s access to the network, use a CoA Request with the Cisco:Avpair=“subscriber:command=disable-host-port” VSA. This command is useful when a host is known to cause problems on the network and network access needs to be immediately blocked for the host. When you want to restore network access on the port, reenable it using a non-RADIUS mechanism.
Additional References
Related Documents
Related Topic
Document Title
Cisco IOS commands
Session Aware Networking commands
Address Resolution Protocol (ARP) commands
ARP configuration tasks
IP Addressing - ARP Configuration Guide
Authentication, authorization, and accounting (AAA) configuration tasks
Authentication Authorization and Accounting Configuration Guide
AAA commands
Cisco IOS Security Command Reference
Technical Assistance
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Feature Information for CoA Support
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.