Network systems, higher-level device and the lower-level apparatus

摘要

PROBLEM TO BE SOLVED: To obtain a more precise round-trip time between devices.;SOLUTION: A network system comprises a plurality of downstream devices and an upstream device connected to the plurality of downstream devices. Each of the downstream devices includes a drift measurement section for measuring an amount of drift in timestamps by using the difference between a timestamp representing the time at the respective downstream devices and a timestamp reported by the upstream device. The upstream device includes an RTT measurement section for measuring a round-trip transmission time between the upstream device and the downstream device. Each of the downstream devices or the upstream device includes an RTT correction section for calculating a corrected round-trip transmission time on the basis of the measured round-trip transmission time and the amount of drift in timestamps.;COPYRIGHT: (C)2013,JPO&INPIT