CHAPTER
10-1
Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
78-11380-10
10
Configuring 802.1x Port-Based Authentication
This chapter describes how to configure IEEE 802.1x port-based authentication on the Catalyst 2950 or
Catalyst 2955 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 10-1
•Configuring 802.1x Authentication, page 10-9
•Displaying 802.1x Statistics and Status, page 10-21

Understanding 802.1x Port-Based Authentication

The IEEE 802.1x standard defines a client-server-based access control and authentication protocol that
prevents unauthorized clients from connecting to a LAN through publicly accessible ports unless they
are properly authenticated. The authentication server authenticates each client co nnected 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 Authentication Protoc ol
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 10-2
•Authentication Initiation and Message Exchange, page 10-3
•Ports in Authorized and Unauthorized States, page 10-4
•802.1x Accounting, page 10-5
•Supported Topologies, page 10-5
•Using 802.1x with Port Security, page 10-6
•Using 802.1x with Voice VLAN Ports, page 10-7