Measuring one-way delay with multiple clock dynamics

A key issue in one-way metrics measurement is the removal of relative clock offset in the situation of without external clock synchronization mechanisms for the end-to-end hosts. The relative clock offset is resulted from clock dynamics including clock adjustment, frequency adjustment and clock drift. Many efforts have been done on the removal of clock skew (related to frequency) in OWD measurement. Most researches are based on the assumption that the clock skew retains constant and without clock adjustments and drifts during measurement. But this does not hold according to our practical measurements and other work. In fact, it is found that host clocks might be subject to gradual or instantaneous clock adjustments and frequency adjustments in operation. We discuss the detection of clock dynamics in OWD measurement, with the time series segmentation technology. An algorithm is proposed to estimate the relative clock offset with only unidirectional probe packets. Experiments results show that the algorithm can provide reasonable clock dynamics detection and informative OWD estimation.