Patent ID: 7058296

Claim:
A method of routing a plurality of demands in an optical network that comprises nodes interconnected by links comprising optical fibers, each demand having two end nodes, the method comprising: a) logically subdividing the network into a plurality of rings, wherein each ring is formed by two link-disjoint paths between a pair of nodes; b) to each of the demands, assigning a ring that contains both of the pertinent end nodes; c) to each of the demands, assigning two mutually link-disjoint paths on the ring from one end node to the other, wherein one said path is a working path and the other said path is a protection path; and d) assigning at least one wavelength channel to each working path and to each protection path, resulting in a working wavelength channel on the working path and a protection wavelength channel on the protection path, wherein: the path and wavelength-channel assignments are carried out so as to drive down a cost function; the cost function includes, for each link, a cost component for placing a further wavelength channel on such link; and said cost component is selected to decrease as the number of already-placed wavelength channels increases, but to jump to a highest value when the number of already-placed wavelength channels reaches the full capacity of one optical fiber.