Planet WGSW-2840 Инструкция по эксплуатации онлайн [57/104] 65303

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

The switch or the client can initiate authentication. If you enable authentication on a port by using the dot1x

port-control auto interface configuration command, the switch must initiate authentication when it determines

that the port link state transitions from down to up. It then sends an EAP-request/identity frame to the client to

request its identity (typically, the switch sends an initial identity/request frame followed by one or more requests for

authentication information). Upon receipt of the frame, the client responds with an EAP-response/identity frame.

However, if during bootup, the client does not receive an EAP-request/identity frame from the switch, the client

can initiate authentication by sending an EAPOL-start frame, which prompts the switch to request the client's

identity

NOTICE:

If 802.1X is not enabled or supported on the network access device, any EAPOL frames from the client are