Device Roles

With 802.1X port-based authentication, the devices in the network have specific roles. (See below figure).

zSupplicant—Requests access to the LAN and switch services and responds to requests from the switch. The workstation must be running 802.1X-compliant software.

zAuthentication server—performs the actual authentication of the host. The authentication server validates the identity of the host and notifies the DSLAM whether or not the host is authorized to access the LAN and DSLAM services. Because the DSLAM acts as the proxy, the authentication service is transparent to the host. In this release, the Remote Authentication Dial-In User Service (RADIUS) security system with Extensible Authentication Protocol (EAP) extensions is the only supported authentication server; it is available in Cisco Secure Access Control Server version 3.0. RADIUS operates in a client/server model in which secure authentication information is exchanged between the RADIUS server and one or more RADIUS clients.

zDSLAM (Authenticator)—Controls the physical access to the network that is based on the authentication status of the host. The DSLAM acts as an intermediary (proxy) between the host and the authentication server, requesting identity information from the host, verifying information with the authentication server, and relaying a response to the host. The DSLAM interacts with the RADIUS client. The RADIUS client encapsulates and decapsulates the EAP frames and interacts with the authentication server.

zWhen the DSLAM receives Extensible Authentication Protocol over LAN (EAPOL) frames and relays them to the authentication server, the Ethernet header is stripped and the remaining EAP frame is reencapsulated in the RADIUS format. The EAP frames are not modified or examined during encapsulation, and the authentication server must support EAP within the native frame format. When the DSLAM receives the frames from the authentication server, the server's frame header is removed, leaving the EAP frame, which is then encapsulated for Ethernet and sent to the host.

IP DSLAM

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