TGPS-9164GT-M12 Series User
Manual
ORing Industrial Networking Corp
132
address as the destination MAC address for EAPOL frames sent
from the switch to the supplicant, since that would cause all
supplicants attached to the port to reply to requests sent from the
switch. Instead, the switch uses the supplicant's MAC address,
which is obtained from the first EAPOL Start or EAPOL Response
Identity frame sent by the supplicant. An exception to this is when
no supplicants are attached. In this case, the switch sends
EAPOL Request Identity frames using the BPDU multicast MAC
address as destination - to wake up any supplicants that might be
on the port.
The maximum number of supplicants that can be attached to a
port can be limited using the Port Security Limit Control
functionality.
MAC-based Auth.
Unlike port-based 802.1X, MAC-based authentication is not a
standard, but merely a best-practices method adopted by the
industry. In MAC-based authentication, users are called clients,
and the switch acts as the supplicant on behalf of clients. The
initial frame (any kind of frame) sent by a client is snooped by the
switch, which in turn uses the client's MAC address as both
username and password in the subsequent EAP exchange with
the RADIUS server. The 6-byte MAC address is converted to a
string in the following form "xx-xx-xx-xx-xx-xx", that is, a dash (-)
is used as separator between the lower-cased hexadecimal digits.
The switch only supports the MD5-Challenge authentication
method, so the RADIUS server must be configured accordingly.
When authentication is complete, the RADIUS server sends a
success or failure indication, which in turn causes the switch to
open up or block traffic for that particular client, using the Port
Security module. Only then will frames from the client be
forwarded on the switch. There are no EAPOL frames involved in
this authentication, and therefore, MAC-based authentication has
nothing to do with the 802.1X standard.
The advantage of MAC-based authentication over port-based
802.1X is that several clients can be connected to the same port
(e.g. through a 3rd party switch or a hub) and still require
individual authentication, and that the clients don't need special
