CoA (Change of Authorization) is a feature that allows ClearPass to dynamically change the authorization and access privileges of a device after it has been authenticated1. CoA uses RADIUS messages to communicate with the network device and instruct it to perform an action, such as reauthenticating the device, applying a new VLAN or user role, or disconnecting the device2.
To enable CoA on a CX switch, the network engineer needs to configure dynamic authorization on the switch, which is a global command that allows the switch to accept RADIUS messages from ClearPass and execute the requested actions3. The network engineer also needs to specify the IP address and shared secret of ClearPass as a dynamic authorization client on the switch3.
To trigger CoA for a specific wired device, the network engineer needs to bounce the switchport, which is an action that temporarily disables and re-enables the port where the device is connected. This forces the device to reauthenticate and receive the new policy from ClearPass. Bouncing the switchport can be done manually by using the interface shutdown and no shutdown commands, or automatically by using ClearPass as a CoA server and sending a RADIUS message with the Port-Bounce-Host AVP (Attribute-Value Pair).