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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 9 Configuring IEEE 802.1x Port-Based Authentication
Configuring IEEE 802.1x Authentication
Configuring a Guest VLAN
When you configure a guest VLAN, clients that are not IEEE 802.1x-capable are put into the guest
VLAN when the server does not receive a response to its EAPOL request/identity frame. Clients that are
IEEE 802.1x-capable but fail authentication are not granted access to the network. The switch supports
guest VLANs in single-host or multiple-hosts mode.
You can enable optional guest VLAN behavior by using the dot1x guest-vlan supplicant global
configuration command. When enabled, the switch does not maintain the EAPOL packet history and
allows clients that fail authentication to access the guest VLAN, regardless of whether EAPOL packets
had been detected on the interface. Clients that fail authentication can access the guest VLAN.
Note Depending on the switch configuration, assigning the client to a guest VLAN can take up to several
minutes.
Beginning in privileged EXEC mode, follow these steps to configure a guest VLAN. This procedure is
optional.
To disable and remove the guest VLAN, use the no dot1x guest-vlan interface configuration command.
The port returns to the unauthorized state.
This example shows how to enable VLAN 9 as an IEEE 802.1x guest VLAN on a port:
Switch(config)# interface fastethernet0/1
Switch(config-if)# dot1x guest-vlan 9
This example shows how to set 3 as the quiet time on the switch, to set 15 as the number of seconds that
the switch waits for a response to an EAP-request/identity frame from the client before resending the
request, and to enable VLAN 2 as an IEEE 802.1x guest VLAN when an IEEE 802.1x port is connected
to a DHCP client:
Switch(config-if)# dot1x timeout quiet-period 3
Switch(config-if)# dot1x timeout tx-period 15
Switch(config-if)# dot1x guest-vlan 2
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Specify the interface to be configured, and enter interface configuration
mode. For the supported interface types, see the
“IEEE 802.1x
Authentication Configuration Guidelines” section on page 9-13.
Step 3
switchport mode access Set the port to access mode.
Step 4
dot1x port-control auto Enable IEEE 802.1x authentication on the port.
Step 5
dot1x guest-vlan vlan-id Specify an active VLAN as an IEEE 802.1x guest VLAN. The range is 1
to 4094.
You can configure any active VLAN except an RSPAN VLAN or a voice
VLAN as an IEEE 802.1x guest VLAN.
Step 6
end Return to privileged EXEC mode.
Step 7
show dot1x interface interface-id Verify your entries.
Step 8
copy running-config startup-config (Optional) Save your entries in the configuration file.