Abstract

This paper investigates the lightpath establishment problem in the optical layer, which arises in multilayer traffic engineering. The static version of the problem is considered, in which the set of requested lightpaths is known initially, and the objective is to set up as many of these lightpaths as possible by assigning the physical layer resources efficiently. In establishing the lightpaths, physical layer impairments are also considered, such that the bit error rates of all established lightpaths should remain within acceptable limits. A heuristic algorithm, called ROLE, is proposed for the solution of this problem. An integer linear programming (ILP) formulation for the static lightpath establishment with physical layer impairments is also developed, which considers the aggregated effect of physical layer impairments. This formulation is used as a performance benchmark for ROLE on smaller-size networks. It also provides upper bounds even when the ILP model cannot be solved to optimality. The performance of ROLE is close to the optimum solutions for all studied problem sets, for which the optimum solution can be obtained. ROLE significantly outperforms previously proposed algorithms in terms of the number of lightpaths established. The effect of switch cross-talk ratio on the problem solution is also investigated.