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802.1X configuration
802.1X overview
The 802.1X protocol was proposed by IEEE 802 LAN/WAN committee for security of wireless
LANs (WLANs). However, it has been widely used on Ethernet as a common port access control
mechanism.
As a port-based network access control protocol, 802.1X authenticates devices connected to the
802.1X-enabled LAN ports to control their access to the LAN.
Architecture of 802.1X
802.1X operates in the typical client/server model and defines three entities: Client, Device, and
Server. See Figure 15.
Figure 15
Architecture of 802.1X
•
Client is an entity seeking access to the LAN. It resides at one end of a LAN segment and is
authenticated by Device at the other end of the LAN segment. Client is usually a user-end
device such as a PC. 802.1X authentication is triggered when an 802.1X-capable client
program is launched on Client. The client program must support Extensible Authentication
Protocol over LAN (EAPOL).
•
Device, residing at the other end of the LAN segment, is the entity that authenticates
connected clients. Device is usually an 802.1X-enabled network device and provides access
ports for clients to the LAN.
•
Server is the entity that provides authentication services to Device. Server, normally a RADIUS
(Remote Authentication Dial-in User Service) server, serves to perform authentication,
authorization, and accounting services for users.
Authentication modes of 802.1X
The 802.1X authentication system employs the Extensible Authentication Protocol (EAP) to
exchange authentication information between the client, switch, and authentication server.
•
Between the client and the switch, EAP protocol packets are encapsulated using EAPOL to be
transferred on the LAN.
•
Between the switch and the RADIUS server, EAP protocol packets can be exchanged in two
modes: EAP relay and EAP termination. In EAP relay mode, EAP packets are encapsulated in
the EAP over RADIUS (EAPOR) packets on the switch, which then can relay the packets to the
RADIUS server. In EAP termination mode, EAP packets are terminated at the switch, converted