H3C S5120-SI Series Command Reference Manual page 791

Description
Use the mac-address timer command to configure the aging timer for dynamic MAC address entries.
Use the undo mac-address timer command to restore the default.
The default of this command is 300 seconds.
Set the aging timer appropriately: a long aging interval may cause the MAC address table to retain
outdated entries and fail to accommodate the latest network changes; a short interval may result in
removal of valid entries and hence unnecessary broadcasts which may affect device performance.
Examples
# Set the aging timer for dynamic MAC address entries to 500 seconds.
<Sysname> system-view
[Sysname] mac-address timer aging 500
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