10-27
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 10 Configuring IEEE 802.1x Port-Based Authentication
Understanding IEEE 802.1x Port-Based Authentication
• When you manually remove an IEEE 802.1x client address from the port security table by using the
no switchport port-security mac-address mac-address interface configuration command, you
should re-authenticate the IEEE 802.1x client by using the dot1x re-authenticate interface
interface-id privileged EXEC command.
• When an IEEE 802.1x client logs off, the port changes to an unauthenticated state, and all dynamic
entries in the secure host table are cleared, including the entry for the client. Normal authentication
then takes place.
• If the port is administratively shut down, the port becomes unauthenticated, and all dynamic entries
are removed from the secure host table.
• Port security and a voice VLAN can be configured simultaneously on an IEEE 802.1x port that is in
either single-host or multiple-hosts mode. Port security applies to both the voice VLAN identifier
(VVID) and the port VLAN identifier (PVID).
You can configure the a
uthentication violation or dot1x violation-mode interface configuration com-
mand so that a port shuts down, generates a syslog error, or discards packets from a new device when it
co
nnects to an IEEE 802.1x-enabled port or when the maximum number of allowed devices have been
a
uthenticated. For more information see the “Maximum Number of Allowed Devices Per Port” section
on page 10-38 and the command reference for this release.
For more information about enabling port security on your switch, see the “C
onfiguring Port Security”
section on page 26-8.
IEEE 802.1x Authentication with Wake-on-LAN
The IEEE 802.1x authentication with wake-on-LAN (WoL) feature allows dormant PCs to be powered
when the switch receives a specific Ethernet frame, known as the magic packet. You can use this feature
in environments where administrators need to connect to systems that have been powered down.
When a host that uses WoL is attached through an IEEE 802.1x port and the host powers off, the
IE
EE 802.1x port becomes unauthorized. The port can only receive and send EAPOL packets, and WoL
m
agic packets cannot reach the host. When the PC is powered off, it is not authorized, and the switch
port is not opened.
When the switch uses IEEE 802.1x authentication with WoL, the switch forwards traffic to unauthorized
IE
EE 802.1x ports, including magic packets. While the port is unauthorized, the switch continues to
bl
ock ingress traffic other than EAPOL packets. The host can receive packets but cannot send packets to
other devices in the network.
Note If PortFast is not enabled on the port, the port is forced to the bidirectional state.
When you configure a port as unidirectional by using the dot
1x control-direction in interface
configuration command, the port changes to the spanning-tree forwarding state. The port can send
packets to the host but cannot receive packets from the host.
When you configure a port as bidirectional by using the dot
1x control-direction both interface
configuration command, the port is access-controlled in both directions. The port does not receive
packets from or send packets to the host.
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