Reliable Design of Communication Networks

Over the past few decades there have been many mathematical models for the design and dimensioning of public and private communication networks. These models have tended to concentrate upon the performance aspects of the network and to determine the link and node capacities which are required to meet prescribed performance objectives of loss and/or delay. The primary objective has been to minimise the cost of (expensive) network plant. However, in recent years with the development of optical fibres having very large capacities available at a relatively cheap cost, the emphasis in network design has shifted from being exclusively performance based, to one in which the users require both performance and reliability/availability as businesses have become more and more dependent on good communications for their effective operation. Design of networks to meet a set of performance constraints has been the subject of extensive investigations over the past two or three decades in relation to both telephony and, more recently, data networks. Very few models have been developed to jointly consider performance and reliability. In this paper, we shall attempt to develop mathematical models which incorporate both performance and reliability criteria. A generic mathematical programming model is presented in section 3. Mathematical models for reliability are often quite difficult to solve because of the large solution state space involved. We shall describe an approach for solving this problem for practical size networks using an heuristic method. In section 4 we discuss a number of different realisations of the generic model in the areas of private circuit switched and Asynchronous Transfer Mode networks. Finally, in section 5.1 a simple 8 node network is investigated for a variety of different network modelling scenarios and solutions obtained using the simple heuristic approach which has been developed.