Patent ID: 9077481
Filing Date: 2015-07-07
Classification: H04J

Abstract:
1. A method of allocating a wavelength to a lightpath in a wavelength multiplex for use in an optical network comprising nodes connected by optical links, wherein the wavelength multiplex is adapted to support lightpaths of two different bitrates, the lightpaths operating on different wavelengths; the method comprising, at a network management system: receiving a request for a new lightpath; computing the new lightpath in response to the request; evaluating quality of transmission, QoT, of the new lightpath; comparing the evaluated QoT of the new lightpath with a threshold and if the QoT is at or above the threshold the method comprises: determining an existing lightpath operating at the higher of the two bitrates and having a shortest wavelength among the lightpaths operating at the higher bitrate in the wavelength multiplex if the new lightpath is to operate at the lower of the two bitrates; and allocating to the new lightpath a wavelength from the wavelength multiplex shorter than said shortest wavelength and separated from said shortest wavelength by at least a defined number of unused wavelengths of the multiplex; or determining an existing lightpath operating at the lower of the two bitrates and having a longest wavelength among the lightpaths operating at the lower bitrate in the wavelength multiplex if the new lightpath is to operate at the higher of the two bitrates; and allocating to the new lightpath a wavelength from the wavelength multiplex longer than said longest wavelength and separated from said longest wavelength by at least the defined number of unused wavelengths of the multiplex.