Performance-driven design and redesign of high-speed local area networks

Although distributed computing over a network of computers has become a reality, its success mainly depends on the performance of the underlying network. In this paper, we consider the problem of designing a local area network with specified cost and performance constraints. The cost and performance of a local area network (LAN) are directly related to its topology. Using the a priori knowledge of the approximate number of users of the network and the kind of communication traffic that must be supported, the designer can optimize the design of the of a LAN for superior performance. Design decisions include the number of LAN segments, number of bridges, assignment of users to segments, and the method to interconnect the segments through bridges. In case of ATM networks, the decisions are regarding the number of ATM switches, the assignment of hosts to switches, and the way to connect switches through cross-connects. While assigning too many users to the same segment may cause large delays due to the sharing of network bandwidth, splitting the LAN into too many segments will increase the cost of the LAN. We report a greedy heuristic algorithm for local area network design. We propose an interesting method to construct good initial solutions to the topology design problem using a heuristic method which is based on the three-opt technique for solving the travelling salesperson problem. Our experimental results indicate that the heuristic algorithm finds good solutions.