This object sets the number of extra entries the admin wants reserved in a hardware-assisted filter CAM to absorb overflow conditions on a specific link, defaulting to 400 if filtering hardware is present and zero otherwise. An admin tunes this reserve to reduce the risk of address-learning failures when a link's MAC address table nears full hardware CAM capacity. For example, an admin managing a busy uplink with many learned addresses might increase this reserve above the 400 default to add headroom against CAM overflow.