CHAPTER
8-1
Catalyst 2940 Switch Software Configuration Guide
78-15507-02
8
Configuring 802.1X Port-Based Authentication
This chapter describes how to configure IEEE 802.1X port-based authentic ation o n the Cat al yst 2 940
switch to prevent unauthorized devices (clients) from gaining access to the network.
Note For complete syntax and usage information for the commands used in this chapter, refer to the command
reference for this release.
This chapter consists of these sections:
•Understanding 802.1X Port-Based Authentication, page 8-1
•Configuring 802.1X Authentication, page 8-6
•Displaying 802.1X Statistics and Status, page 8-16

Understanding 802.1X Port-Based Authentication

The IEEE 802.1X standard defines a client-server-based access control and authentication protocol that
restricts unauthorized clients from connecting to a LAN th roug h p ubli cly acc essi ble po rts. Th e
authentication server authenticates each client connected to a switch port before making available any
services offered by the switch or the LAN.
Until the client is authenticated, 802.1X access control allows only Extensible Authent icat ion Prot o col
over LAN (EAPOL), Cisco Discovery Protocol (CDP), and Spanning Tree Protocol (STP) traffic through
the port to which the client is connected. After authentication is successful, normal traffic can pass
through the port.
These sections describe 802.1X port-based authentication:
•Device Roles, page 8-2
•Authentication Initiation and Message Exchange, page 8-3
•Ports in Authorized and Unauthorized States, page 8-4
•Supported Topologies, page 8-4
•Using 802.1X with Voice VLAN Ports, page 8-5