ORiNG IGS-9168GP series, Руководство пользователя

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IGS-9168GP User’s Manual
ORing Industrial Networking Corp 122
In an 802.1X network environment, the user is called the supplicant, the
switch is the authenticator, and the RADIUS server is the authentication
server. The authenticator acts as the man-in-the-middle, forwarding
requests and responses between the supplicant and the authentication
server. Frames sent between the supplicant and the switch are special
802.1X frames, known as EAPOL (EAP Over LANs) frames which
encapsulate EAP PDUs (RFC3748). Frames sent between the switch
and the RADIUS server is RADIUS packets. RADIUS packets also
encapsulate EAP PDUs together with other attributes like the switch's IP
address, name, and the supplicant's port number on the switch. EAP is
very flexible as it allows for different authentication methods, like
MD5-Challenge, PEAP, and TLS. The important thing is that the
authenticator (the switch) does not need to know which authentication
method the supplicant and the authentication server are using, or how
many information exchange frames are needed for a particular method.
The switch simply encapsulates the EAP part of the frame into the
relevant type (EAPOL or RADIUS) and forwards it.
When authentication is complete, the RADIUS server sends a special
packet containing a success or failure indication. Besides forwarding the
result to the supplicant, the switch uses it to open up or block traffic on
the switch port connected to the supplicant.
Note: in an environment where two backend servers are enabled, the
server timeout is configured to X seconds (using the authentication
configuration page), and the first server in the list is currently down (but
not considered dead), if the supplicant retransmits EAPOL Start frames
at a rate faster than X seconds, it will never be authenticated because
the switch will cancel on-going backend authentication server requests
whenever it receives a new EAPOL Start frame from the supplicant.
Since the server has not failed (because the X seconds have not
expired), the same server will be contacted when 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.
a. Single 802.1X
In port-based 802.1X authentication, once a supplicant is successfully
authenticated on a port, the whole port is opened for network traffic. This
allows other clients connected to the port (for instance through a hub) to