Chapter 3 Authentication for FortiOS 5.0 : Authentication servers : FortiAuthenticator servers
  
FortiAuthenticator servers
FortiAuthenticator is an Authentication, Authorization, and Accounting (AAA) server, that includes a RADIUS server, an LDAP server, and can replace the FSSO Collector Agent on a Windows AD network. Multiple FortiGate units can use a single FortiAuthenticator for FSSO, remote authentication, and FortiToken management.
For more information, see the FortiAuthenticator Administration Guide.