esaProbeStatsSumOfSqAbsR2PJitter is a 64-bit performance counter that reports the sum-of-squares of the absolute-value one-way jitter (magnitude of the delay swing regardless of direction), in microseconds, from the reflector back to the probe, applicable to Layer 3 ICMP-timestamp and Layer 2 Y.1731 probes, for the interval that is still being actively collected (the live bin). Because it discards the sign of the swing, this absolute-jitter figure from the reflector back to the probe gives a technician a single severity number to alarm on without watching the positive and negative jitter counters separately. For example, combining this live sum-of-squares value with the bin's packet count and delay sum lets the technician compute the variance of absolute jitter from the reflector back to the probe to judge, right now, whether the circuit is consistently mediocre or wildly erratic.