JPS647826A - Switching method for optical line - Google Patents

Abstract

PURPOSE:To shorten the instantaneous disconnection time at the time of a switching operation by considering a propagation time of a synchronizing signal between first and second switching controllers, and determining an output timing of a switching control signal of a first or second switching machine, and an output timing of the synchronizing signal. CONSTITUTION:Prior to switching of an optical line, a synchronizing signal is sent and received between the first and the second switching controllers 30, 40, and a propagation delay time of the synchronizing signal to the second switching controller from the first switching controller, caused by existence of first and second MODEMs 33, 43 and a synchronizing control line 50 is measured. At the time of switching of the optical lines 1, 2, the synchronizing signal is outputted from the first switching controller 30, and thereafter, by being delayed by a propagation delay time of the synchronizing signal, a switching control signal for bringing the first switching machine 10 to a switching operation is outputted from the first switching controller 30. In such a way, by considering a propagation time of the synchronizing signal between the first and the second switching controllers 30, 40 an output timing of the switching control signal of the first or the second switching machines 10, 20, and an output timing of the synchronizing signal are determined. In such a way, an instantaneous disconnection time at the time of a switching operation can be shortened.