User manual

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Understanding 802.1x Port-based and MAC-based Network Access Control
The original intent behind the development of 802.1x was to leverage the characteristics of point-to-point in LANs.
As any single LAN segment in such infrastructures has no more than two devices attached to it, one of which is a
Bridge Port. The Bridge Port detects events that indicate the attachment of an active device at the remote end of
the link, or an active device becoming inactive. These events can be used to control the authorization state of the
Port and initiate the process of authenticating the attached device if the Port is unauthorized. This is the Port-
Based Network Access Control.
Port-Based Network Access Control
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802.1X
Client
802.1X
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802.1X
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802.1X
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802.1X
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802.1X
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802.1X
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802.1X
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802.1X
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Network access controlled port
Network access uncontrolled port
RADIUS
Server
Ethernet Switch
Figure 9- 7. Example of Typical Port-Based Configuration
Once the connected device has successfully been authenticated, the Port then becomes Authorized, and all
subsequent traffic on the Port is not subject to access control restriction until an event occurs that causes the Port
to become Unauthorized. Hence, if the Port is actually connected to a shared media LAN segment with more than
one attached device, successfully authenticating one of the attached devices effectively provides access to the LAN
for all devices on the shared segment. Clearly, the security offered in this situation is open to attack.