Setting the MAC Learning LimitTo 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 modemac learning-limit address_limitThree options are available with the mac learning-limit command:– dynamic– no-station-move– station-moveNOTE: An SNMP trap is available for mac learning-limit station-move. No other SNMP traps are availablefor MAC Learning Limit, including limit violations.mac learning-limit DynamicThe 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 MAClearning limit, entries created on this port are static by default. When you configure the dynamic option, learned MAC addresses arestored 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 systems do not detect station moves in which aMAC address learned off of a MAC-limited port is learned on another port on same line card. Therefore, Dell Networking OS does nottake any configured station-move violation action. When a MAC address is relearned on any other line card (any line card except theone to which the original MAC-limited port belongs), the station-move is detected and the system takes the configured the violationaction.mac learning-limit mac-address-stickyUsing sticky MAC addresses allows you to associate a specific port with MAC addresses from trusted devices. If you enable stickyMAC, the specified port retains any dynamically-learned addresses and prevents them from being transferred or learned on otherports.If you configure mac-learning-limit and you enabled sticky MAC, all dynamically-learned addresses are converted to stickyMAC addresses for the selected port. Any new MAC addresses learned on this port is converted to sticky MAC addresses.To save all sticky MAC addresses into a configuration file that can be used as a startup configuration file, use the write configcommand. If the number of existing MAC addresses is fewer than the configured mac learn limit, any additional MAC addresses areconverted to sticky MACs on that interface. To remove all sticky MAC addresses from the running config file, disable sticky MAC anduse the write config command.When you enable sticky mac on an interface, dynamically-learned MAC addresses do not age, even if you enabled mac-learning-limit dynamic. If you configured mac-learning-limit and mac-learning-limit dynamic and you disabled stickyMAC, any dynamically-learned MAC addresses ages.mac learning-limit station-moveThe station-move option, allows a MAC address already in the table to be learned off of another interface. For example, if youdisconnect a network device from one interface and reconnect it to another interface, the MAC address is learned on the newinterface. When the system detects this “station move,” the system clears the entry learned on the original interface and installs anew entry on the new interface.394 Layer 2
