A VOSS switch with EAPOL enabled will send RADIUS reachability packets every 180 seconds using RADIUS reachability mode use-radius. The Access-Request will contain the User Name Attribute with value reachme. If this username does not exist on the RADIUS server an Access-Reject (3) message is seen every time the Access-Request is sent.

In Extreme Access Control add the username reachme with password reachme in the Local  Password Repository and the Access-Request will return an Access-Accept message.

A new installation of Control will need at least one Authentication Rule setup under the Configuration>AAA>Default>Advanced AAA Configuration which will use the Local Authentication option for the Authentication Method.

I always change the Default setting from Basic to Advanced AAA Configuration to allow multiple Authentication Rules so can search Active Directory as well as Local.