FGSW-2620VM User’s Manual
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Authentication Initiation and Message Exchange
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Ports in Authorized and Unauthorized States
Device Roles
With 802.1X port-based authentication, the devices in the network have specific roles as shown below.
z
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.)
z
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.
z
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 client and the authentication server, requesting
identity information from the client, verifying that information with the authentication server, and relaying a
response to the client. The switch includes the RADIUS client, which is responsible for encapsulating and
decapsulating the Extensible Authentication Protocol (EAP) frames and interacting with the authentication
server. When the switch receives EAPOL frames and relays them to the authentication server, the Ethernet
header is stripped and the remaining EAP frame is re-encapsulated 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 switch receives 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 client.
Authentication Initiation and Message Exchange
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