This object counts times this specific association's remote receive window hit zero. Each occurrence here is a moment this device had to stop sending to that peer entirely, so a rising count on one particular association, while others stay at zero, singles out a specific peer that is chronically overloaded or slow to drain its buffers. This counter climbing steadily for the association to one MGC while staying flat for all others points specifically at that MGC being under-resourced relative to the signaling load being sent to it.