This value sets the lower limit, below the upper limit and measured over a 1-second interval in the unit chosen by hh3cStormCtrlUnicastUnit, that unicast traffic must fall under before a controlled port returns to normal forwarding. An admin uses the gap between the upper and lower values to add hysteresis so the port does not rapidly flap between controlled and normal status. For example, a unicast upper limit of 5000 pps paired with a lower limit of 4000 pps keeps the port blocked until traffic clearly subsides.