AAA network diagram

AAA uses a client/server model. The client runs on the access device, or the network access server (NAS), which authenticates user identities and controls user access. The server maintains user information centrally. See Figure 1.

To access networks or resources beyond the NAS, a user sends its identity information to the NAS. The NAS transparently passes the user information to AAA servers and waits for the authentication, authorization, and accounting result. Based on the result, the NAS determines whether to permit or deny the access request.

AAA has various implementations, including HWTACACS, LDAP, and RADIUS. RADIUS is most often used.

You can use different servers to implement different security functions. For example, you can use an HWTACACS server for authentication and authorization, and use a RADIUS server for accounting.

You can choose the security functions provided by AAA as needed. For example, if your company wants employees to be authenticated before they access specific resources, you would deploy an authentication server. If network usage information is needed, you would also configure an accounting server.

The device performs dynamic password authentication.