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Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 23 Configuring Port-Based Traffic Control
Configuring Port Security
The sticky secure MAC addresses do not automatically become part of the configuration file, which is
the startup configuration used each time the switch restarts. If you save the sticky secure MAC addresses
in the configuration file, when the switch restarts, the interface does not need to relearn these addresses.
If you do not save the sticky secure addresses, they are lost.
If sticky learning is disabled, the sticky secure MAC addresses are converted to dynamic secure
addresses and are removed from the running configuration.
The maximum number of secure MAC addresses that you can configure on a switch is set by the
maximum number of available MAC addresses allowed in the system. This number is the total of
available MAC addresses, including those used for other Layer 2 functions and any other secure MAC
addresses configured on interfaces.
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 four violation modes, based on the action to be taken if a
violation occurs:
• protect—When the number of secure MAC addresses reaches the maximum limit allowed on the
port, packets with unknown source addresses are dropped until you remove a sufficient number of
secure MAC addresses to drop below the maximum value or increase the number of maximum
allowable addresses. You are not notified that a security violation has occurred.
Note We do not recommend configuring the protect violation 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 maximum limit allowed on the
port, packets with unknown source addresses are dropped until you remove a sufficient number of
secure MAC addresses to drop below the maximum value or increase the number of maximum
allowable addresses. In this mode, you are notified that a security violation has occurred. An SNMP
trap is sent, a syslog message is logged, and the violation counter increments.
• shutdown—A port security violation causes the interface to become error-disabled and to shut down
immediately, and the port LED turns off. 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 shut
down interface configuration commands. This is the default mode.
• shutdown vlan—Use to set the security violation mode per-VLAN. In this mode, the VLAN is error
disabled instead of the entire port when a violation occurs
Table 23-1 shows the violation mode and the actions taken when you configure an interface for port
security.