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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter10 Configuring IEEE 802.1x Port-Based Authentication
Understanding IEEE 802.1x Port-Based Authentication
Beginning with Cisco IOS Release 12.2(55)SE, you can filter out verbose system messages generated
by the authentication manager. The filtered content typically relates to authentication success. You can
also filter verbose messages for 802.1x authentication and MAB authentication. There is a separate
command for each authentication method:
•The no authentication logging verbose global configuration command filters verbose messages
from the authentication manager.
•The no dot1x logging verbose global configuration command filters 802.1x authentication verbose
messages.
•The no mab logging verbose global configuration command filters MAC authentication bypass
(MAB) verbose messages
For more information, see the command reference for this release.
Ports in Authorized and Unauthorized States
During 802.1x authentication, depending on the switch port state, the switch can grant a client access to
the network. The port starts in the unauthorized state. While in this state, the port that is not configured
as a voice VLAN port disallows all ingress and egress traffic except for 802.1x authentication, CDP, and
STP packets. When a client is successfully authenticated, the port changes to the authorized state,
allowing all traffic for the client to flow normally. If the port is configured as a voice VLAN port, the
port allows VoIP traffic and 802.1x protocol packets before the client is successfully authenticated.
If a client that does not support 802.1x authentication connects to an unauthorized 802.1x port, the
switch requests the client’s identity. In this situation, the client does not respond to the request, the port
remains in the unauthorized state, and the client is not granted access to the network.
In contrast, when an 802.1x-enabled client connects to a port that is not running the 802.1x standard, the
client initiates the authentication process by sending the EAPOL-start frame. When no response is
received, the client sends the request for a fixed number of times. Because no response is received, the
client begins sending frames as if the port is in the authorized state.
You control the port authorization state by using the authentication port-control or dot1x port-control
interface configuration command and these keywords:
•force-authorized—disables 802.1x authentication and causes the port to change to the authorized
state without any authentication exchange required. The port sends and receives normal traffic
without 802.1x-based authentication of the client. This is the default setting.
•force-unauthorized—causes the port to remain in the unauthorized state, ignoring all attempts by
the client to authenticate. The switch cannot provide authentication services to the client through the
port.
authentication timer dot1x timeout Set the timers.
authentication violation {protect |
restrict | shutdown}
dot1x violation-mode {shutdown
| restrict | protect}
Configure the violation modes that occur when a
new device connects to a port or when a new
device connects to a port after the maximum
number of devices are connected to that port.
Table10-2 Authentication Manager Commands and Earlier 802.1x Commands (continued)
The authentication manager
commands in Cisco IOS
Release12.2(50)SE or later
The equivalent 802.1x commands in
Cisco IOS Release 12.2(46)SE and
earlier Description