RGPS-92222GCP-NP Series User Manual
ORing Industrial Networking Corp.
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link is up, and any client on the port will be disallowed network access.
Port-based 802.1X
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
