User's Manual

Configuration Guide of XGS-5240-Series
47-4
Fig 3-2 the Work Mechanism of 802.1x
 EAP messages adopt EAPOL encapsulation format between the PAE of the supplic
ant system and the PAE of the authenticator system in the environment of LAN.
 Between the PAE of the authenticator system and the RADIUS server, there are t
wo methods to exchange information: one method is that EAP messages adopt EA
POR (EAP over RADIUS) encapsulation format in RADIUS protocol; the other is th
at EAP messages terminate with the PAE of the authenticator system, and adopt t
he messages containing RAP (Password Authentication Protocol) or CHAP (Challen
ge Handshake Authentication Protocol) attributes to do the authentication interaction
with the RADIUS server.
 When the user pass the authentication, the authentication server system will send t
he relative information of the user to authenticator system, the PAE of the authenti
cator system will decide the authenticated/unauthenticated status of the controlled p
ort according to the authentication result of the RADIUS server.
47.1.3 The Encapsulation of EAPOL Messages
1. The Format of EAPOL Data Packets
EAPOL is a kind of message encapsulation format defined in 802.1x protocol, and
is mainly used to transmit EAP messages between the supplicant system and the auth
enticator system in order to allow the transmission of EAP messages through the LAN.
In IEEE 802/Ethernet LAN environment, the format of EAPOL packet is illustrated in th
e next figure. The beginning of the EAPOL packet is the Type/Length domain in MAC f
rames.
Fig 3-3 the Format of EAPOL Data Packet
PAE Ethernet Type: Represents the type of the protocol whose value is 0x888E.
Protocol Version: Represents the version of the protocol supported by the sender o
f EAPOL data packets.
Type: represents the type of the EAPOL data packets, including: