AAA clients Makes requests and communicates with the AAA server, sending usernames and other parameters.
AAA server Receives authentication requests from the clients, compares them to a database, authorizes the client, and begins accounting tasks.
User or accounts database Can be Open Database Connectivity (ODBC), Lightweight Directory Access Protocol (LDAP), Novell Directory Services (NDS), or Windows NT, 2000, or 2003. It allows an administrator to easily manage users and groups with different levels of permissions.
