Mathematical model and heuristic strategy for SDH meshed networks dimensioning

This paper concerns optimized dimensioning of SDH meshed networks with line restoration. A mathematical model of the network is presented with the purpose of minimizing the total cost of STM-N systems between nodes. The model jointly determines the routing of the working traffic and the spare capacity allocation required for the full restoration of the demand affected by any single link failure at a time. Some practical features have been included, such as flow integrality between network nodes, STM-N modularity and the possibility to superpose two hierarchical level systems in the links. The problem is solved using integer linear programming techniques. Since the execution time depends greatly on the number of integer variables that grow exponentially according to the size of the network, a heuristic has been developed that relaxes integer variables and, after iterative rounding off procedures, obtains the solution integrality. Practical applications are presented which allow the heuristic evaluation