Patent ID: 8249454

Claim:
An optical communication system in which an optical line terminating apparatus and a plurality of optical network apparatuses are connected together via an optical line terminating apparatus side optical fiber connected to the optical line terminating apparatus, a plurality of optical fibers respectively connected to the plurality of optical network apparatuses, and an optical branching section to connect the optical line terminating apparatus side optical fiber and the plurality of optical fibers, wherein the optical line terminating apparatus includes a wavelength division multiplexing section, a first optical coupler, a light receiving section, a light transmitting section, a first light reception section, a first detection section, and a first control section, the optical branching section includes one optical line terminating apparatus side port, a plurality of optical network apparatus side branch ports, a plurality of light cut-off sections, an optical splitter, a second optical coupler, a second light reception section, a second detection section, and a second control section, in the optical line terminating apparatus, the first optical coupler branches a signal from the wavelength division multiplexing section to the first light reception section and the light receiving section and outputs it, the first light reception section converts the optical signal into an electrical signal and outputs it to the first detection section, and when an abnormal signal light is inputted, the first detection section uses a dynamic bandwidth assignment function to detect that the signal from which optical network apparatus is abnormal, the first control section forms, based on the detection result, light cut-off control information indicating that the signal from which optical network apparatus is to be cut off, and outputs the light cut-off control information by the transmitting section through the wavelength division multiplexing section, the optical branching section receives the light cut-off control information through the optical line terminating apparatus side optical fiber, the second optical coupler branches the signal from the optical line terminating apparatus to the optical splitter and the second light reception section and outputs it, the second light reception section converts the optical signal into an electrical signal and outputs it to the second detection section, the second detection section detects the light cut-off control information, the second control section controls the light cut-off section corresponding to the optical network apparatus side optical fiber connected to the optical network apparatus indicated by the light cut-off control information, and the light cut-off section cuts off the optical signal sent from the optical network apparatus.