Patent ID: 7106965

Claim:
A wavelength division multiplex transmission system which distributes transmission signals to be transmitted among a plurality of wavelength components, converts said signals into WDM signals, and transmits said WDM signals to a WDM transmission network, and which restores WDM signals from said WDM transmission network into said transmission signals; comprising an optical transmission device and optical receiving device, in which said optical transmission device comprises at least a plurality of operating-system optical transmission units associated with one standby-system optical transmission unit, and said optical receiving device comprises at least a plurality of operating-system optical receiving units associated with one standby-system optical receiving unit; wherein either said operating-system optical transmission units, or said standby-system optical transmission unit, or both, have optical transmission unit internal defect avoidance means which, upon the occurrence of a prescribed number or fewer of wavelength component transmission defects, executes avoidance of defects within said optical transmission unit; wherein said operation-system optical transmission unit and said standby-system optical transmission unit are configured to transfer said transmission signals at fixed respective wavelengths, such that said standby-system optical transmission unit is configured to transmit transmission signals using a transmission wavelength component different from that of the operating-system transmission units associated with a wavelength component transmission defect; and wherein said standby-system optical receiving unit is configured to receive a receive wavelength component different from that of the operating-system receive units associated with a wavelength component receive defect.