Patent ID: 7068931

Claim:
An alarm control method for an optical communications network in which a transmitting terminal transmits an optical signal to a receiving terminal through an optical transmission line, comprising the steps of: at the transmitting terminal, a) inputting an optical signal from a signal transmitter; b) producing an alarm information signal indicating whether the optical signal is normally inputted; c) transmitting the optical signal and an optical control signal including the alarm information signal to the receiving terminal through the optical transmission line; at the receiving terminal, d) receiving the optical control signal and the optical signal from the transmitting terminal, e) determining whether the optical signal is normally received by a signal receiver; and f) when the optical signal is not normally received by the signal receiver, controlling transmission of a receiver-side alarm signal to a management system depending on whether the alarm information signal included in the optical control signal indicates that the optical signal has been normally inputted at the transmitting terminal, wherein the step (f) comprises the steps of: when the alarm information signal indicates that the optical signal has not been normally inputted at the transmitting terminal, suppressing transmission of the receiver-side alarm signal to the management system; and when the alarm information signal indicates that the optical signal has been normally inputted at the transmitting/terminal, transmitting the receiver-side alarm signal to the management system.