Method for determining data transmission state in data communication system

摘要

An upstream communication device notifies a downstream communication device of NEXP(0), which indicates a data reception state at the upstream communication device, and the downstream communication device compares it with NEXP(1), which indicates a data reception state at the downstream communication device. By comparing the reception states (arrival/non-arrival) of each unit of data, it is possible to determine whether or not each unit of data is normally transmitted, and, if data is lost, it is possible to identify a link in which the data is lost.