Patent ID: 7925163

Claim:
A method for assigning colors to wavelength demands for transmitting multiple optical signals in an optical network between originating nodes and terminating nodes, the optical network comprising the originating nodes, the terminating nodes and a plurality of intermediate nodes interconnected by a plurality of links, the plurality of links each being capable of transmitting a respective predetermined maximum number of separate optical signals using separate colors, the method comprising: formulating a mathematical model representing the optical network and the wavelength demands; minimizing an objective function of the model, the objective function representing a total cost of the optical network as a function of an assignment of the colors, the objective function including a sum of at least the following quantities: a weighted summation of distances transmitted in each color in the optical network; a sum of all binary elements in a first matrix uu[r, l, c] wherein r represents individual routes used to meet the wavelength demands, l represents individual links included in a particular route, and c represents individual color channels used in particular links in particular routes, the sum of all binary elements in the first matrix uu[r, l, c] being weighted to favor fewer links per color channel in each route; a sum of all elements in a second matrix vv[r, c] wherein each element represents a number of colors used in a color channel c in a route r, the sum of all elements in the second matrix vv[r, c] being weighted to force, when possible, a single color per color channel in each route; and a weighted count of nodes traversed by each route, whereby routes with larger numbers of nodes are penalized; and assigning the colors to the wavelength demands and identifying one or more of the intermediate nodes for color changeovers whereby the objective function is minimized.