A test user account is used in the rare case where a RADIUS server ignores RADIUS messages as mentioned in the AAA RADIUS server operation status section. Consequently, when messages are ignored, the router places the RADIUS server out of service. The test user account can keep a RADIUS server in service by periodically sending RADIUS requests to the server. The RADIUS server, while randomly ignoring other subscriber RADIUS requests, must respond to the test user requests. A RADIUS server is in service if it replies to RADIUS messages before the down-timeout timer expires. The default down-timeout default value is the timeout value multiplied by the retry value, but it is also configurable. The test user account has a configurable interval value, and it is recommended that this value be configured to be less than the down-timeout value for it to be useful. The test user account only applies to RADIUS authentication.
Typically, a RADIUS server always responds to all RADIUS requests, and therefore it is not recommended that a test user account be used unless it is absolutely necessary for specific types of servers. The test user account creates extra load for the processor and can affect scaling. The test user account can be used with a Python script (for example, adding additional attributes to the test user account during an access-request operation).