Cisco Catalyst 2960 Series, Configuration Manual

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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 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.
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.
Note
• 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
This table shows the violation mode and the actions taken when you configure an interface for port security.
Table 135: Security Violation Mode Actions
Shuts down
port Violation
counter
increments Displays
error
message
19
Sends syslog
message Sends SNMP
trap Traffic is
forwarded
18
Violation
Mode
No No No No No No protect
No Yes No Yes Yes No restrict
Yes Yes No No No No shutdown
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
1483
Information About Port Security