Patent ID: 7756417

Claim:
A light-transmitting apparatus for demultiplexing an input signal completing wavelength division multiplexing into signals of wavelength components with wavelengths different from each other and for transmitting each of said wavelength components through a transmission line provided for transmission of said wavelength components, said light-transmitting apparatus comprising: a wavelength-count-detecting unit detecting the number of wavelengths of wavelength components included in said input signal and determining whether the number of wavelengths is normal or abnormal; a plurality of extraction units provided for each of said wavelength components, said extraction units extracting an identifier set in each of said signals of said wavelength components; a plurality of identifier-detecting units each associated with one of said extraction units and determining whether or not each of said identifiers extracted by said extraction units is normal; and a judgment unit judging whether or not each of the components of the input signal is down or each of said identifier is abnormal for each of said wavelength components on the basis of a detection result output by said wavelength-count-detecting unit and a detection result output by said identifier-detecting unit associated with said wavelength component, wherein each of said signals of said wavelength components is a frame signal and each said identifier is set in a predetermined position of said frame and identifies a channel.