Allied Telesis AT-S39 - Manual (Page 194)

Section II: Local and Telnet Management
194
By default, authentication protocol is disabled on an AT-8000 Series
switch. Once you activate it, you will need to provide the following
information:
❑ Which authentication protocol you want to use. Only one
authentication protocol can be active on a switch at a time.
❑ IP addresses of up to three authentication servers.
❑ The encryption key used by the authentication servers.
Note
For more information on TACACS+, refer to the RFC 1492 standard.
For more information on RADIUS, refer to the RFC 2865 standard.