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interface/VLAN. After the limit is reached, the system drops all traffic from a device with an unlearned
MAC address.
This section describes the following:
• mac learning-limit Dynamic
• mac learning-limit station-move
• Learning Limit Violation Actions
• Setting Station Move Violation Actions
• Recovering from Learning Limit and Station Move Violations
Dell Networking OS Behavior: When configuring the MAC learning limit on a port, the configuration is
accepted (becomes part of running-config and show mac learning-limit interface) before
the system verifies that sufficient CAM space exists. If the CAM check fails, a message displays:
%E90MH:5 %ACL_AGENT-2-ACL_AGENT_LIST_ERROR: Unable to apply access-list Mac-
Limit on GigabitEthernet 5/84
In this case, the configuration is still present in the running-config and show output. Remove the
configuration before re-applying a MAC learning limit with a lower value. Also, ensure that you can view
the Syslog messages on your session.
Setting the MAC Learning Limit
To set a MAC learning limit on an interface, use the following command.
• Specify the number of MAC addresses that the system can learn off a Layer 2 interface.
INTERFACE mode
mac learning-limit address_limit
Three options are available with the mac learning-limit command:
NOTE: An SNMP trap is available for mac learning-limit station-move. No other SNMP
traps are available for MAC Learning Limit, including limit violations.
mac learning-limit Dynamic
The MAC address table is stored on the Layer 2 forwarding information base (FIB) region of the CAM.
The Layer 2 FIB region allocates space for static MAC address entries and dynamic MAC address entries.
When you enable MAC learning limit, entries created on this port are static by default. When you
configure the dynamic option, learned MAC addresses are stored in the dynamic region and are subject
to aging. Entries created before this option is set are not affected.
Dell Networking OS Behavior: If you do not configure the dynamic option, the MXL switch does not
detect station moves in which a MAC address learned off of a MAC-limited port is learned on another
port on the same stack unit or different stack.
528
Layer 2