Device Roles - Cisco WS-C2948G-GE-TX Configuration Manual

Understanding How 802.1x Authentication Works
always open. The controlled port is open only when the device that is connected to the port has been
authorized by 802.1x. After this authorization takes place, the controlled port opens, allowing normal
traffic to pass. You can restrict traffic in both directions, or you can restrict the incoming traffic only.

Device Roles

With 802.1x port-based authentication, the devices in the network have specific roles. (See
Figure 31-1 802.1x Device Roles
Workstations
(supplicants)
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•
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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
31-2
Catalyst switch
Host—Requests access to the LAN and switch services and responds to requests from the switch.
The workstation must be running 802.1x-compliant software.
IEEE 802.1x uses the term supplicant for client or host. In this publication, we use host
Note
instead of supplicant because host is used in the Catalyst 4500 series CLI syntax.
Authentication server—Performs the actual authentication of the host. The authentication server
validates the identity of the host and notifies the switch whether or not the host is authorized to
access the LAN and switch services. Because the switch acts as the proxy, the authentication service
is transparent to the host. In this release, the Remote Authentication Dial-In User Service (RADIUS)
security system with Extensible Authentication Protocol (EAP) extensions is the only supported
authentication server; it is available in Cisco Secure Access Control Server version 3.0. RADIUS
operates in a client/server model in which secure authentication information is exchanged between
the RADIUS server and one or more RADIUS clients.
Switch—Controls the physical access to the network that is based on the authentication status of the
host. The switch acts as an intermediary (proxy) between the host and the authentication server,
requesting identity information from the host, verifying information with the authentication server,
and relaying a response to the host. The switch interacts with the RADIUS client. The RADIUS
client encapsulates and decapsulates the EAP frames and interacts with the authentication server.
When the switch receives Extensible Authentication Protocol over LAN (EAPOL) frames and relays
them to the authentication server, the Ethernet header is stripped and the remaining EAP frame is
reencapsulated in the RADIUS format. The EAP frames are not modified or examined during
encapsulation, and the authentication server must support EAP within the native frame format.
When the switch receives the frames from the authentication server, the server's frame header is
removed, leaving the EAP frame, which is then encapsulated for Ethernet and sent to the host.
Chapter 31
Authentication
server
(RADIUS)
Configuring 802.1x Authentication
Figure 31-1.)
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