Users 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 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.
mac learning-limit mac-address-sticky
Using sticky MAC addresses allows you to associate a specic port with MAC addresses from trusted devices. If you enable sticky
MAC, the specied port retains any dynamically learned addresses and prevents them from being transferred or learned on other
ports.
If you congure 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 this port is converted to sticky MAC addresses.
To save all sticky MAC addresses into a conguration le that can be used as a startup conguration le, use the write config
command. If the number of existing MAC addresses is fewer than the congured mac learn limit, any additional MAC addresses are
converted to sticky MACs on that interface. To remove all sticky MAC addresses from the running cong le, disable sticky MAC and
use 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 congured mac-learning-limit and mac-learning-limit dynamic and you disabled sticky
MAC, any dynamically learned MAC addresses ages.
mac learning-limit station-move
The station-move option, allows a MAC address already in the table to be learned o 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
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Layer 2