1-11 AAA OverviewIntroduction to AAAAAA is the acronym for the three security functions: authentication, authorization and accounting. Itprovides a uniform framework for you to configure these three functions to implement network securitymanagement.z Authentication: Defines what users can access the network,z Authorization: Defines what services can be available to the users who can access the network,andz Accounting: Defines how to charge the users who are using network resources.Typically, AAA operates in the client/server model: the client runs on the managed resources side whilethe server stores the user information. Thus, AAA is well scalable and can easily implement centralizedmanagement of user information.AuthenticationAAA supports the following authentication methods:z None authentication: Users are trusted and are not checked for their validity. Generally, thismethod is not recommended.z Local authentication: User information (including user name, password, and some other attributes)is configured on this device, and users are authenticated on this device instead of on a remotedevice. Local authentication is fast and requires lower operational cost, but has the deficiency thatinformation storage capacity is limited by device hardware.z Remote authentication: Users are authenticated remotely through RADIUS or HWTACACSprotocol. This device (for example, a 3Com series switch) acts as the client to communicate withthe RADIUS or TACACS server. You can use standard or extended RADIUS protocols inconjunction with such systems as iTELLIN/CAMS for user authentication. Remote authenticationallows convenient centralized management and is feature-rich. However, to implement remoteauthentication, a server is needed and must be configured properly.AuthorizationAAA supports the following authorization methods:z Direct authorization: Users are trusted and directly authorized.z Local authorization: Users are authorized according to the related attributes configured for theirlocal accounts on this device.z RADIUS authorization: Users are authorized after they pass RADIUS authentication. In RADIUSprotocol, authentication and authorization are combined together, and authorization cannot beperformed alone without authentication.z HWTACACS authorization: Users are authorized by a TACACS server.
