RADIUS protocol uses ports 1812 and 1813
For authentication and authorization, the RADIUS user sends a request to the Network Access Sever (NAS) for access to a network resource.
For accounting, the RADIUS user sends a request to the RADIUS Accounting server, using Start, Update and Stop to provide information on the session duration and usage.
RADIUS specifies Access-Request for authentication and authorization, and Accounting-Request for accounting:
RADIUS Authentication & Authorization - RFC 2865
RADIUS Accounting - RFC 2866
RADIUS Support for EAP - RFC3579