This per-interface setting, indexed by ifIndex, enables or disables caching of MAC-learned events specifically on that interface. It must be turned on for each interface where an admin wants learned-MAC notifications, on top of the global hh3cMACInformationEnabled switch, giving fine-grained control over which ports are monitored. For example, an admin could enable hh3cMACLearntEnable only on uplink ports to track new devices entering the network while leaving noisy access ports unmonitored.