Synchronizing system in digital communication line

Abstract

A synchronizing system in a digital communication line comprises a plurality of local switches for storing at least one digital line and monitoring a first piece of busy information when a clock source is already present, the local switches, if a first new clock source occurs while the first busy information is indicating no busy state, being capable of transmitting a master right request to turn the busy information to the busy state and to specify the first new clock source as a master clock and, on receiving a master right specification with respect to the master right request, being capable of outputting the first new clock source as the master clock; and a master switch connected to the plurality local switches in a star manner, by a link transmission line for transmitting control information including the master clock, master right request and master right specification, for monitoring a second piece of busy information indicating a busy state, the master switch, if a second new clock source occurs while the second busy information is indicating no busy state, being capable of transmitting the second new clock source as a master clock and, if the second new clock source competes with the first new clock source in the local switches that has output the master right request, being capable of arbitrating the competition between the first and second new clock sources and selecting one of the clock sources to turn the busy information to the busy state and, if the first clock source is selected, outputting the master right specification to the local switches that have transmitted the master right request.