Patent ID: 9197347
Filing Date: 2015-11-24
Classification: H04J

Abstract:
1. A noise suppression method for use in an optical transmission system which includes a plurality of nodes transmitting a WDM optical signal, and in which first node equipment drops an optical signal transmitted via a first wavelength channel from the WDM optical signal and guides the dropped optical signal to a communication device, the noise suppression method comprising: transmitting a failure signal that represents whether or not a failure occurs for each of the plurality of wavelength channels in the WDM optical signal; transmitting a shutoff signal that represents whether or not a shutoff operation for shutting off an optical output is instructed for the respective wavelength channels; and shutting off the first wavelength channel when the failure signal represents that a failure occurs in the first wavelength channel and the shutoff signal represents that the shutoff operation is instructed for the first wavelength channel, wherein when second node equipment arranged on a first route for transmitting an optical signal with the first wavelength channel to the first node equipment detects a failure in the first wavelength channel, the second node equipment transmits the failure signal that represents a failure occurs in the first wavelength channel to the first node equipment via the first route, when the first node equipment receives the failure signal that represents a failure occurs in the first wavelength channel from the second node equipment, the first node equipment transmits the shutoff signal that represents the shutoff operation is instructed for the first wavelength channel toward the second node equipment via the first route, third node equipment shuts off an optical output of the first wavelength channel, after the third node equipment relays the failure signal that represents a failure occurs in the first wavelength channel, and when the third node equipment receives the shutoff signal that represents the shutoff operation is instructed for the first wavelength channel, and wherein the first node equipment periodically or constantly transmits the shutoff signal toward the second node equipment via the first route regardless of the failure signal.