Security Violations - Cisco Catalyst 3750 Software Configuration Manual

Configuring Port Security
The maximum number of secure MAC addresses that you can configure on a switch is determined by the
maximum number of available MAC addresses allowed in the system. This number is determined by the
active Switch Database Management (SDM) template. See
This number represents 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:
•
•
You can configure the interface for one of three violation modes, based on the action to be taken if a
violation occurs:
•
•
•
Table 18-1
security.
Table 18-1 Security Violation Mode Actions
Violation Traffic is
Mode forwarded
protect No
restrict No
shutdown No
1. Packets with unknown source addresses are dropped until you remove a sufficient number of secure MAC addresses.
2. The switch returns an error message if you manually configure an address that would cause a security violation.
Catalyst 3750 Metro Switch Software Configuration Guide
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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.
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
Note
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. An SNMP trap is sent, a syslog message is logged, and the
violation counter increments. 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.
shows the violation mode and the actions taken when you configure an interface for port
Sends SNMP Sends syslog
1
trap message
No No
Yes Yes
Yes Yes
Chapter 18 Configuring Port-Based Traffic Control
Chapter 6, "Configuring SDM Templates."
Displays error Violation counter
2
message increments
No No
No Yes
No Yes
Shuts down
port
No
No
Yes
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