iES12G
User’s
Manual
UM-iES12G-1.72.2-EN.docx
Pages 130 of 166
© 2020 IS5 COMMUNICATIONS INC. ALL RIGHTS RESERVED
Label
Description
supplicant retransmits EAPOL Start frames at a rate faster than X seconds, then it will
never get authenticated, because the switch will cancel on-going backend
authentication server requests whenever it receives a new EAPOL Start frame from
the supplicant. And since the server hasn't yet failed (because the X seconds haven't
expired), the same server will be contacted upon the next backend authentication
server request from the switch. This scenario will loop forever. Therefore, the server
timeout should be smaller than the supplicant's EAPOL Start frame retransmission
rate.
MAC-based
Auth.
Unlike 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
supplicant software to authenticate. The disadvantage is that MAC addresses can
be spoofed by malicious users - equipment whose MAC address is a valid RADIUS
user can be used by anyone. Also, only the MD5-Challenge method is supported.
The maximum number of clients that can be attached to a port can be limited using
the Port Security Limit Control functionality.
Port State
The current state of the port. It can undertake one of the following values:
Globally Disabled
: NAS is globally disabled.
Link Down
: NAS is globally enabled, but there is no link on the port.
Authorized
: the port is in Force Authorized or a single-supplicant mode and the
supplicant is authorized.
Unauthorized:
the port is in Force Unauthorized or a single-supplicant mode and the
supplicant is not successfully authorized by the RADIUS server.
X Auth/Y Unauth
: the port is in a multi-supplicant mode. Currently X clients are
authorized and Y are unauthorized.
Restart
Two buttons are available for each row. The buttons are only enabled when
authentication is globally enabled and the port's Admin State is in an EAPOL-based
or MAC-based mode.
Clicking these buttons will not cause settings changed on the page to take effect.
Reauthenticate:
schedules a reauthentication whenever the quiet-period of the port
runs out (EAPOL-based authentication). For MAC-based authentication,
reauthentication will be attempted immediately.
The button only has effect on successfully authenticated clients on the port and will not
cause the clients to be temporarily unauthorized.
Reinitialize:
forces a reinitialization of the clients on the port and hence a
reauthentication immediately. The clients will transfer to the unauthorized state while
the reauthentication is in progress.
