Packet Delay Monitoring without a GPS

This paper illustrates a technique to characterize one-way packet delays. In the spirit of [9] such technique does not depend on external clock synchronization facilities: instead, it computes the relative skew of the two clocks, and uses this information to characterize one-way packet delays. We focus on the applicability of such technique to a network monitoring environment, and perform an extensive test that includes second order clock frequency variations. We conclude that the approach is especially suited to estimate jitter, and other “local” characteristics of one-way delay variation. It can be helpful also to evaluate second order parameters of one-way delay, like standard deviation, when second order variations of clock frequency, usually due to temperature variations, are compensated by hardware. This result makes one-way delay variations measurement widely accessible to Internet hosts, at a cost which is overall comparable with that of a ping.