Port-Based Network Access Control - D-Link DES-3526 - Switch - Stackable User Manual

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xStack DES-3500 Series Layer 2 Stackable Fast Ethernet Managed Switch User Manual

Port-Based Network Access Control

The original intent behind the development of 802.1x was to leverage the characteristics of point-to-point in LANs. Any single
LAN segment in such an 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.
RADIUS
Server
Ethernet Switch
...
802.1X 802.1X 802.1X 802.1X 802.1X 802.1X 802.1X
802.1X 802.1X
Client Client Client Client Client Client Client
Client Client
Network access controlled port
Network access uncontrolled port
Figure 7- 10. Example of Typical Port-Based Configuration
Once the connected Client 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.
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