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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 21 Configuring Port-Based Traffic Control
Configuring Port Security
Security Violations
It is a security violation when one of these situations occurs:
•
The maximum number of secure MAC addresses have been added to the address table, and a station
whose MAC address is not in the address table attempts to access the interface.
•
An address learned or configured on one secure interface is seen on another secure interface in the
same VLAN.
You can configure the interface for one of three violation modes, based on the action to be taken if a
violation occurs:
•
protect—When the number of secure MAC addresses reaches the limit allowed on the port, packets
with unknown source addresses are dropped until you remove a sufficient number of secure MAC
addresses or increase the number of maximum allowable addresses. You are not notified that a
security violation has occurred.
Note
We do not recommend enabling the protect mode on a trunk port. The protect mode disables
learning when any VLAN reaches its maximum limit, even if the port has not reached its
maximum limit.
•
restrict—When the number of secure MAC addresses reaches the limit allowed on the port, packets
with unknown source addresses are dropped until you remove a sufficient number of secure MAC
addresses or increase the number of maximum allowable addresses. In this mode, you are notified
that a security violation has occurred. Specifically, an SNMP trap is sent, a syslog message is
logged, and the violation counter increments.
•
shutdown—In this mode, a port security violation causes the interface to immediately become
error-disabled, and turns off the port LED. It also sends an SNMP trap, logs a syslog message, and
increments the violation counter. When a secure port is in the error-disabled state, you can bring it
out of this state by entering the errdisable recovery cause psecure-violation global configuration
command, or you can manually re-enable it by entering the shutdown and no shutdown interface
configuration commands. This is the default mode.
shows the violation mode and the actions taken when you configure an interface for port
security.
Table 21-1
Security Violation Mode Actions
Violation Mode
Traffic is
forwarded
1
1.
Packets with unknown source addresses are dropped until you remove a sufficient number of secure MAC addresses.
Sends SNMP
trap
Sends syslog
message
Displays error
message
2
2.
The switch will return an error message if you manually configure an address that would cause a security violation.
Violation
counter
increments
Shuts down port
protect
No
No
No
No
No
No
restrict
No
Yes
Yes
No
Yes
No
shutdown
No
Yes
Yes
No
Yes
Yes