H3C S5100-SI Operation Manual page 250

Figure 1-8 802.1x authentication procedure (in EAP relay mode)
EAPOL
Supplicant system
PAE
EAPOL - Start
EAP- Request / Identity
EAP- Response / Identity
EAP- Request / MD5 challenge
EAP- Response / MD5 challenge
EAP-Success
Handshake request
[ EAP- Request / Identity ]
Handshake response
[ EAP- Response / Identity ]
EAPOL -Logoff
The detailed procedure is as follows:
A supplicant system launches an 802.1x client to initiate an access request by sending
an EAPoL-start packet to the switch, with its user name and password provided. The
802.1x client program then forwards the packet to the switch to start the authentication
process.
Upon receiving
EAP-request/identity packet to ask the 802.1x client for the user name.
The 802.1x client responds by sending an EAP-response/identity packet to the switch
with the user name contained in it. The switch then encapsulates the packet in a
RADIUS Access-Request packet and forwards it to the RADIUS server.
Upon receiving the packet from the switch, the RADIUS server retrieves the user name
from the packet, finds the corresponding password by matching the user name in its
database, encrypts the password using a randomly-generated key, and sends the key
to the switch through an RADIUS access-challenge packet. The switch then sends the
key to the 802.1x client.
Upon receiving the key (encapsulated in an EAP-request/MD5 challenge packet) from
the switch, the client program encrypts the password of the supplicant system with the
key and sends the encrypted password (contained in an EAP-response/MD5 challenge
packet) to the RADIUS server through the switch. (Normally, the encryption is
irreversible.)
Authenticator system
PAE
(EAP- Response / Identity)
( EAP- Request / MD5 challenge)
( EAP- Response / MD5 challenge)
Port authorized
......
Port unauthorized
the authentication
1-7
EAPOR
RADUIS
RADIUS Access - Request
RADIUS Access -Challenge
RADIUS Access - Request
RADIUS Access -Accept
(EAP-Success)
Handshake timer
request packet,
server
the switch sends an