D-Link DES-3250TG User Manual - page 111

D-Link DES-3250TG Standalone Layer 2 Switch

Authentication Process 

Utilizing the three roles stated above, the 802.1x protocol provides a stable and secure way of authorizing and authenticating 

users attempting to access the network. Only EAPOL traffic is allowed to pass through the specified port before a successful 

authentication is made. This port is “locked” until the point when a Client with the correct username and password (and MAC 

address if 802.1x is enabled by MAC address) is granted access and therefore successfully “unlocks” the port. Once unlocked, 

normal traffic is allowed to pass through the port. The following figure displays a more detailed explanation of how the 

authentication process is completed between the three roles stated above. 

Figure 7- 62. The 802.1x Authentication Process 

The D-Link implementation of 802.1x allows network administrators to choose between two types of Access Control used on 

the Switch, which are: 

1.  Port-Based Access Control – This method requires only one user to be authenticated per port by a remote RADIUS 

server to allow the remaining users on the same port access to the network.  

2.  MAC-Based Access Control – Using this method, the Switch will automatically learn up to three MAC addresses by 

port and set them in a list. Each MAC address must be authenticated by the Switch using a remote RADIUS server 

before being allowed access to the Network.  

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. 

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