Wavelength assignment to minimize the number of SONET ADMs in WDM rings

Optical wavelength division multiplexing (WDM) rings are being deployed to support SONET/SDH self-healing rings. The cost of such a system is dominated by the SONET add/drop multiplexers (ADM). To minimize the system cost, algorithms must be developed to assign wavelengths to lightpaths in the system so that the number of ADM required is minimized. This problem of optimal wavelength assignment to minimize the number of SONET ADM is NP-hard. In this paper, we develop an integer linear programming (ILP) formation for this problem, propose a new wavelength assignment heuristic, and evaluate the existing and the newly proposed heuristic using the ILP formation. We conclude that the performance of the newly proposed heuristic is very close to optimal.