This sets the count threshold of egress buffer overflow events for ABR traffic that, within the corresponding alert period, triggers a threshold-crossing alert on this port. Because ABR flow control is expected to react to congestion signals, such as EFCI marking per pportEFCIMarking, before overflows become severe, this threshold on this specific port is generally the tolerance level for how many overflow events indicate that adaptive flow control is not keeping up, rather than every single overflow being independently alarming. A rising rate of ABR overflow events that repeatedly crosses this threshold on this port, despite EFCI marking being enabled, would suggest the ABR sources on that circuit are not responding to congestion signaling as expected.