This value sets how often, in seconds, the interface sends out a Layer-3 MAC advertisement packet using its own receive MAC address as the source, so downstream switches refresh their MAC-address-table entries pointing at this router interface. Admins tune this timer to keep downstream switches from aging out and forgetting which port leads to this router's Layer-3 interface, which could otherwise cause traffic to be flooded instead of switched directly to it. With its default value of 60, the interface would send a refresh advertisement roughly once a minute.