Brocade FastIron Ethernet Switch Security Configuration Guide - Manual (Page 172)

Communication between the devices
For communication between the devices, 802.1X port security uses the Extensible Authentication
Protocol (EAP), defined in RFC 2284. The 802.1X standard specifies a method for encapsulating EAP
messages so that they can be carried over a LAN. This encapsulated form of EAP is known as EAP
over LAN (EAPOL). The standard also specifies a means of transferring the EAPOL information
between the Client/Supplicant, Authenticator, and Authentication Server.
EAPOL messages are passed between the Port Access Entity (PAE) on the Supplicant and the
Authenticator. The following figure shows the relationship between the Authenticator PAE and the
Supplicant PAE.
FIGURE 2 Authenticator PAE and supplicant PAE
Authenticator PAE - The Authenticator PAE communicates with the Supplicant PAE, receiving
identifying information from the Supplicant. Acting as a RADIUS client, the Authenticator PAE passes
the Supplicant information to the Authentication Server, which decides whether the Supplicant can
gain access to the port. If the Supplicant passes authentication, the Authenticator PAE grants it access
to the port.
Supplicant PAE - The Supplicant PAE supplies information about the Client to the Authenticator PAE
and responds to requests from the Authenticator PAE. The Supplicant PAE can also initiate the
authentication procedure with the Authenticator PAE, as well as send log off messages.
Controlled and uncontrolled ports
A physical port on the device used with 802.1X port security has two virtual access points: a controlled
port and an uncontrolled port. The controlled port provides full access to the network. The uncontrolled
port provides access only for EAPOL traffic between the Client and the Authentication Server. When a
Client is successfully authenticated, the controlled port is opened to the Client. The following figure
illustrates this concept.
Communication between the devices
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