Patent ID: 7308201

Claim:
A method for carrying multiple traffic data channels in a transmission path in an optical communication network, including wavelength division multiplexed (WDM) channels carried in a first wavelength band and at least one service channel wavelength associated with the WDM channels and carried on at least one further wavelength that is separate from the first wavelength band, the method comprising: adding at least one WDM channel wavelength to the transmission path or dropping at least one of the WDM channel wavelengths from the transmission path utilizing a first set of filter elements; dropping the at least one service channel wavelength from the transmission path utilizing an extraction element, the extraction element being arranged upstream of the first set of filter elements, adding the at least one service channel wavelength to the transmission path utilizing a combining element, the combining element being arranged downstream of the first set of filter elements, the extraction element and the combining element being adapted to drop and add a second wavelength band in addition to the at least one service channel wavelength, and passively relay the first wavelength band, the second wavelength band being separate from the first wavelength band and carrying at least one optical traffic data channel; arranging the at least one service channel wavelength and the second wavelength band on the same side of the wavelength spectrum relative to the first wavelength band; and utilizing the extraction element and the combining element for dropping and adding, respectively, all wavelengths on the side of the spectrum containing the at least one service channel wavelength and the second wavelength band.