The Mechanism Of An 802.1X Authentication System - 3Com 4210 9-Port Configuration Manual

stores user information, such as user name, password, the VLAN a user belongs to, priority, and
the ACLs (access control list) applied.
The four basic concepts related to the above three entities are PAE, controlled port and uncontrolled
port, the valid direction of a controlled port and the way a port is controlled.
PAE
A PAE (port access entity) is responsible for implementing algorithms and performing protocol-related
operations in the authentication mechanism.
The authenticator system PAE authenticates the supplicant systems when they log into the LAN
and controls the status (authorized/unauthorized) of the controlled ports according to the
authentication result.
The supplicant system PAE responds to the authentication requests received from the
authenticator system and submits user authentication information to the authenticator system. It
also sends authentication requests and disconnection requests to the authenticator system PAE.
Controlled port and uncontrolled port
The Authenticator system provides ports for supplicant systems to access a LAN. Logically, a port of
this kind is divided into a controlled port and an uncontrolled port.
The uncontrolled port can always send and receive packets. It mainly serves to forward EAPoL
packets to ensure that a supplicant system can send and receive authentication requests.
The controlled port can be used to pass service packets when it is in authorized state. It is blocked
when not in authorized state. In this case, no packets can pass through it.
Controlled port and uncontrolled port are two properties of a port. Packets reaching a port are
visible to both the controlled port and uncontrolled port of the port.
The valid direction of a controlled port
When a controlled port is in unauthorized state, you can configure it to be a unidirectional port, which
sends packets to supplicant systems only.
By default, a controlled port is a unidirectional port.
The way a port is controlled
A port of a 3Com series switch can be controlled in the following two ways.
Port-based authentication. When a port is controlled in this way, all the supplicant systems
connected to the port can access the network without being authenticated after one supplicant
system among them passes the authentication. And when the authenticated supplicant system
goes offline, the others are denied as well.
MAC address-based authentication. All supplicant systems connected to a port have to be
authenticated individually in order to access the network. And when a supplicant system goes
offline, the others are not affected.

The Mechanism of an 802.1x Authentication System

IEEE 802.1x authentication system uses the extensible authentication protocol (EAP) to exchange
information between supplicant systems and the authentication servers.
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