Administrator Guide

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 system does not detect station moves in which a MAC
address learned off of a MAC-limited port is learned on another port on same line card. Therefore, any configured violation response to
detected station moves is not performed. When a MAC address is relearned on any other line card (any line card except the one to which
the original MAC-limited port belongs), the station-move is detected and the system takes the configured the violation action.
mac learning-limit mac-address-sticky
Using sticky MAC addresses allows you to associate a specific port with MAC addresses from trusted devices. If you enable sticky MAC,
the specified port retains any dynamically-learned addresses and prevents them from being transferred or learned on other ports. Up to
1000 sticky entries are supported on a port.
If you configure mac-learning-limit and you enabled sticky MAC, all dynamically-learned addresses are converted to sticky MAC
addresses for the selected port. Any new MAC addresses learned on the port are 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 config
command. If the number of existing MAC addresses is fewer than the configured MAC learning limit, additional MAC addresses are
converted to sticky MACs addresse on the port. To remove all sticky MAC addresses from the running configuration file, disable sticky
MAC and enter 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 sticky MAC,
any dynamically-learned MAC address ages.
mac learning-limit station-move
The mac learning-limit station-move command allows a MAC address already in the table to be learned from 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.
mac learning-limit no-station-move
The no-station-move option, also known as “sticky MAC,” provides additional port security by preventing a station move.
When you configure this option, the first entry in the table is maintained instead of creating an entry on the new interface. no-station-
move is the default behavior. Entries created before you set this option are not affected.
To display a list of all interfaces with a MAC learning limit, use the following command.
Display a list of all interfaces with a MAC learning limit.
EXEC Privilege mode
show mac learning-limit
Learning Limit Violation Actions
Learning limit violation actions are user-configurable.
To configure 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.
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Layer 2