1-11 AAA ConfigurationThis chapter includes these sections:z Introduction to AAAz Introduction to RADIUSz Protocols and Standardsz AAA Configuration Task Listz Configuring AAAz Configuring RADIUSz AAA Configuration Examplesz Troubleshooting AAAIntroduction to AAAAuthentication, Authorization, and Accounting (AAA) provides a uniform framework for configuringthese three security functions to implement network security management.AAA usually uses a client/server model, where the client runs on the network access server (NAS) andthe server maintains user information centrally. In an AAA network, a NAS is a server for users but aclient for the AAA servers, as shown in Figure 1-1.Figure 1-1 AAA networking diagramWhen a user tries to establish a connection to the NAS and to obtain the rights to access other networksor some network resources, the NAS authenticates the user or the corresponding connection. The NAScan transparently pass the user’s AAA information to the server (RADIUS server). The RADIUSprotocol defines how a NAS and a server exchange user information between them.In the AAA network shown in Figure 1-1, there are two servers. You can determine the authentication,authorization and accounting methods according to the actual requirements.The three security functions are described as follows:z Authentication: Identifies remote users and judges whether a user is legal.
