TP-Link JetStream T1600G-28TS User Manual page 218

7. The switch changes the state of the corresponding port to accepted state to allow the
supplicant system access the network. And then the switch will monitor the status of
supplicant by sending hand-shake packets periodically. By default, the switch will force the
supplicant to log off if it cannot get the response from the supplicant for two times.
8. The supplicant system can also terminate the authenticated state by sending EAPOL-Logoff
packets to the switch. The switch then changes the port state from accepted to rejected.
(2) EAP Terminating Mode
In this mode, packet transmission is terminated at authenticator systems and the EAP packets are
mapped into RADIUS packets. Authentication and accounting are accomplished through RADIUS
protocol.
In this mode, PAP or CHAP is employed between the switch and the RADIUS server. This switch
supports the PAP terminating mode. The authentication procedure of PAP is illustrated in the
following figure.
In PAP mode, the switch encrypts the password and sends the user name, the
randomly-generated key, and the supplicant system-encrypted password to the RADIUS server for
further authentication. Whereas the randomly-generated key in EAP-MD5 relay mode is generated
by the authentication server, and the switch is responsible to encapsulate the authentication
packet and forward it to the RADIUS server.
802.1X Timer

In 802.1 x authentication, the following timers are used to ensure that the supplicant system, the
switch, and the RADIUS server interact in an orderly way:
Supplicant system timer (Supplicant Timeout): This timer is triggered by the switch
(1)
after the switch sends a request packet to a supplicant system. The switch will resend the
request packet to the supplicant system if the supplicant system fails to respond in the
specified timeout period.
(2) RADIUS server timer (Server Timeout): This timer is triggered by the switch after the
switch sends an authentication request packet to RADIUS server. The switch will resend
the authentication request packet if the RADIUS server fails to respond in the specified
timeout period.
Figure 13-20 PAP Authentication Procedure
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