1. A method for designing a large network having a plurality of n nodes interconnected by a plurality of links by satisfying connectivity constraints, the method comprising: dividing the n nodes into k clusters, for a range of values of k; computing a near-optimal design for each of the k clusters to select the links interconnecting the nodes in each cluster, wherein said computing step is performed by branch-and-bound technique; determining a near-optimal set of links for full set of the n nodes by combining the designs for each of the k clusters, wherein said determining step is performed by dynamic programming technique, and said near-optimal set of links being nearly smallest possible number of said links.