Vivotek AW-GEV-264A Series, Руководство пользователя

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User Manual rev. 1.2. Aug. 2015
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
Port Configuration :
The table has one row for each port on the selected switch and a number of columns, which
are:

Port :
The port number for which the configuration below applies.

Admin State :
If NAS is globally enabled, this selection controls the port's authentication mode. The
following modes are available:

Force Authorized :
In this mode, the switch will send one EAPOL Success frame when the port link comes up,
and any client on the port will be allowed network access without authentication.

Force Unauthorized :
In this mode, the switch will send one EAPOL Failure frame when the port link comes up,
and any client on the port will be disallowed network access.

Port-based 802.1X :
In the 802.1X-world, 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. EAPOL frames encapsulate
EAP PDUs (RFC3748). Frames sent between the switch and the RADIUS server are
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, in that it allows for different authentication methods, like
MD5-Challenge, PEAP, and TLS. The important thing is that the authenticator (the switch)
doesn't 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 this decision to the supplicant, the switch
uses it to open up or block traffic on the switch port connected to the supplicant
N
OTE
:
Suppose two backend servers are enabled and that
the server timeout is configured to X seconds (using the AAA
configuration page), and suppose that the first server in the
list is currently down (but not considered dead).
Now, if the 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.

Single 802.1X :
In port-based 802.1X authentication, once a supplicant is successfully authenticated on a