Eecient Interconnection Designs for Switch-based Local Area Networks 1

Today, with the proliferation of switch-based local area network standards, such as ATM (Asynchronous Transfer Mode), HIPPI (HIgh Performance Parallel Interface) and Fibre Channel, the issue of the eecient interconnection among connection-oriented switches arises. This paper presents a study of eecient arrangements of switches intended to support a local area network environment. This multi-switch interconnection problem is described and distinguished from previously studied interconnection networks such as multistage interconnection networks (for multiprocessors or telephone switching exchanges), and wide-area telephone networks. Given a number of station nodes attached to a set of switches, minimal hardware requirements (number of dedicated I/O ports for inter-switch communications, or number of inter-switch links) as well as the inter-connection topology which supports the maximal aggregate network throughput are sought. This problem is shown to be NP-Complete. Network conngurations based upon switch usage and station node distribution are presented. A network connguration based upon switch usage and station node distribution with superior performance to other conngurations, in terms of maximizing network throughput or resource sharing, is analyzed. Lower bounds on the necessary minimal number of inter-switch links, and maximal number of nonblocking station nodes are derived. Finally, in cases where less than the minimal amount of hardware necessary to support the maximal aggregate network throughput is provided, blocking probabilities are derived. The results of this paper are directly applicable to connection-oriented switch-based networks, such as ATM, HIPPI or Fibre Channel networks.