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40-3
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 40 Configuring 802.1X Port-Based Authentication
About 802.1X Port-Based Authentication
Figure 40-1 802.1X Device Roles
•
Client—The workstation that requests access to the LAN, and responds to requests from the switch.
The workstation must be running 802.1X-compliant client software.
• Authenticator—Controls physical access to the network based on the authentication status of the
client. The Catalyst 4500 series switch acts as an intermediary between the client and the
authentication server, requesting identity information from the client, verifying that information
with the authentication server, and relaying a response to the client. The switch encapsulates and
decapsulates the Extensible Authentication Protocol (EAP) frames and interacts with the RADIUS
authentication server.
When the switch receives 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 frames from the
authentication server, the frame header is removed from the server, leaving the EAP frame, which
is then encapsulated for Ethernet and sent to the client.
Note The Catalyst 4500 series switches must be running software that supports the RADIUS client
and 802.1X.
• Authentication server—Performs the actual authentication of the client. The authentication server
validates the identity of the client and notifies the switch that the client is authorized to access the
LAN and switch services. (The only supported authentication server is the RADIUS authentication
server with EAP extensions; it is available in Cisco Secure Access Control Server version 3.2 and
later releases.)
802.1X and Network Access Control
Network Access Control is a feature that allows port access policies to be influenced by the antivirus
posture of the authenticating device.
Antivirus posture includes such elements as the operating system running on the device, the operating
system version, whether antivirus software is installed and what version of antivirus signatures is
available. If the authenticating device has a NAC-aware 802.1X supplicant and the authentication server
is configured to support NAC using 802.1X, antivirus posture information is automatically included as
part of the 802.1X authentication exchange.
For information on NAC, refer to the URL:
http://www.cisco.com/en/US/netsol/ns617/index.html
Client
Workstations
Supplicants
Authenticator
Authentication
server
94158
Catalyst 4500 Network
Access Switch
RADIUS