Allocation of multicast nodes in wavelength-routed networks

We investigate the allocation of multicast nodes and formalize it as splitter placement in wavelength-routed networks (SP-WRN) problem. The SP-WRN problem entails the placement of multicast nodes so that the overall network blocking probability is minimized. To gain a deeper insight into the computational complexity of the SP-WRN problem, we define a graph-theoretic version of the splitter placement problem (SPG), and show that even SPG is NP-complete. We develop three heuristics for the SP-WRN problem with different degrees of trade-off between computation time an quality of solution. The first heuristic uses CPLEX, the second heuristic is based on a greedy approach, and the third heuristic employs simulated annealing. Numerical examples demonstrate that: (i) no more than 50% of the cross-connects need to be multi-case capable, and (ii) the iterative simulated annealing heuristic provides fast near-optimal solutions