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The standard approach of using multi-commodity network flow (MCNF) techniques for designing optimal WDM networks often lead to computationally difficult Mixed Integer Linear Programs (MILP) which work only on small networks. Modern Operations Research (OR) techniques may be helpful when developing efficient algorithms for large WDM networks. This paper explores the Branch, Price and Cut techniques for designing optimal WDM optical networks. We have studied a well-known problem in WDM networks - non-bifurcated traffic grooming over a specified logical topology. The standard way to solve this problem is to view it as a MCNF problem and solve the resulting MILP using a commercial MILP solver package, such as the ILOG CPLEX to give us an optimum traffic grooming strategy. The number of binary variables and the number of constraints of the MCNF problems increases with the network size and tools such as the CPLEX solver takes increasingly longer time. We have shown how we can take advantage of the structural properties of this problem and solve it efficiently using modern Operations Research techniques.