esaProbeHistoryNumNegP2RJitter is a 64-bit performance counter that reports the count of occurrences of negative one-way jitter (packet-to-packet delay variation), in microseconds, from the probe to the reflector, for a completed interval that has already closed and been archived into the rolling history log. Negative (a packet arriving earlier than the one before it) jitter from the probe to the reflector is exactly the kind of packet-to-packet delay variation that causes stutter in voice and video traffic riding over the same service. For example, comparing this occurrence count of negative jitter from the probe to the reflector across successive archived bins shows whether the events were a one-bin blip or a recurring pattern worth escalating.