Administrator Guide

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 o 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 congure 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 aected.
Dell Networking OS Behavior: If you do not congure the dynamic option, the MXL switch does not detect station moves in
which a MAC address learned o of a MAC-limited port is learned on another port on the same stack unit or dierent stack.
mac learning-limit station-move
The station-move option, allows a MAC address already in the table to be learned o of another interface.
For example, if you disconnect a network device from one interface and reconnect it to another interface, the MAC address is
learned on the new interface. When the system detects this “station move,” the system clears the entry learned on the original
interface and installs a new entry on the new interface.
Learning Limit Violation Actions
To congure the system to take an action when the MAC learning limit is reached on an interface and a new address is received
using one the following options with the mac learning-limit command, use the following commands.
• Generate a system log message when the MAC learning limit is exceeded.
INTERFACE mode
learn-limit-violation log
• Shut down the interface and generate a system log message when the MAC learning limit is exceeded.
INTERFACE mode
learn-limit-violation shutdown
Setting Station Move Violation Actions
no-station-move is the default behavior. You can congure the system to take an action if a station move occurs using one the
following options with the
mac learning-limit command.
To display a list of interfaces congured with MAC learning limit or station move violation actions, use the following commands.
• Generate a system log message indicating a station move.
INTERFACE mode
station-move-violation log
460
Layer 2