Device Roles 
With 802.1X port-based authentication, the devices in the network have specific roles as shown below. 
 
 
Figure 4-11-1 
 
  Client—the device (workstation) that requests access to the LAN and switch services and 
responds to requests from the switch. The workstation must be running 802.1X-compliant 
client software such as that offered in the Microsoft Windows XP operating system. (The 
client is the supplicant in the IEEE 802.1X specification.)  
 
  Authentication server—performs the actual authentication of the client. The authentication 
server validates the identity of the client and notifies the switch whether or not the client is 
authorized to access the LAN and switch services. Because the switch acts as the proxy, the 
authentication service is transparent to the client. 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.   
 
  Switch  (802.1X device)—controls the physical access to the network based on the 
authentication status of the client. The switch acts as an intermediary (proxy) between the