In large enterprise networks, the task of administering passwords on each device can be simplified by doing the user authentication centrally on a server. Authentication is the action of determining who the user is and whether he or she is allowed access to the switch. Authorization is the action of determining what the user is allowed to do on the system.
Accounting is the action of collecting data related to resource usage.
You can access the CLI through the console port or via Telnet. Using the aaa authentication login command and the following keywords, you create one or more lists of authentication methods that are tried at login. The lists are used with the login authentication line configuration command. The keyword list-name is any character string used to name the list you are creating. The method keyword refers to the actual method the authentication algorithm tries, in the sequence entered.