H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 383)

35-2
Server is the entity that provides authentication services to Device. Server, normally running
RADIUS (Remote Authentication Dial-in User Service), 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, device, and authentication server.
Between the client and the device, EAP protocol packets are encapsulated using EAPOL to be
transferred on the LAN.
Between the device 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 EAP
over RADIUS (EAPOR) packets on the device, and then relayed by device to the RADIUS server.
In EAP termination mode, EAP packets are terminated at the device, converted to RADIUS
packets either with the Password Authentication Protocol (PAP) or Challenge Handshake
Authentication Protocol (CHAP) attribute, and then transferred to the RADIUS server.
Basic Concepts of 802.1X
These basic concepts are involved in 802.1X: controlled port/uncontrolled port, authorized
state/unauthorized state, and control direction.
Controlled port and uncontrolled port
A device provides ports for clients to access the LAN. Each port can be regarded as a unity of two
logical ports: a controlled port and an uncontrolled port. Any packets arriving at the port are visible to
both of the logical ports.
The uncontrolled port is always open in both the inbound and outbound directions to allow EAPOL
protocol packets to pass, guaranteeing that the client can always send and receive authentication
packets.
The controlled port is open to allow data traffic to pass only when it is in the authorized state.
Authorized state and unauthorized state
A controlled port can be in either authorized state or unauthorized state, which depends on the
authentication result, as shown in Figure 35-2 .