The Research Of Methods For IP Over WDM System Optimal Design

The rapid development in WDM is making the transformation of fiber communication from a transmission method to the networking technology. The optimal design of optical networks, which are based on lightpaths routing, is becoming a very important issue to Internet Service Providers. In this paper, the methods for optical network designing are researched, the main contributions are listed below:1). The problems of traffic optimal bifurcated and non-bifurcated routingThrough potential function, the objective - minimization of network congestion - is converted to a continue, differential expression in which loads of all links in the network are considered. We also present the way to tune potential construction arguments to control different loaded links'"voice"in the objective function and accelerate the convergence process. Based on the flow deviation method, optimal operations, which are the main part of the optimal processes, are designed for the two traffic routing problems.The virtual bandwidth usage is presented to loose the constraints for valid solutions and smooth the difference between requirement matrix and link bandwidth.2). The problem of lightpaths optimal routingLightpaths optimal routing is analyzed mathematically and divided into two sub-problems, shortest path problem and small-scale linear programming model. A bifurcated routing algorithm is developed and the sub-problems are solved to find an optimal solution in minute-scale running time.Considering the wavelength continuity constraint, the RWA (Routing and Wavelength Assignment) problem is transformed into lightpaths routing problem over a larger-scale network that consist of many copies of the original network. So, it is natural and reasonable to apply lightpaths optimal routing algorithm to RWA problem.3). Logical topology designWe present a genetic algorithm to realize the optimization. The algorithm, different from other similar methods, gets excellent convergence characteristic from high-quality initial population, and more heuristic genetic operators that quicken the elimination of"bad"genes. To make the logical topology design to take the consideration of physical network, we present lightpath liabilityξij, which is incorporated into requirement matrix using equation"rs′d =rsd+β?ξsd".