Selecting Capacities in Computer Communication Systems

This paper considers the selection of capacities, in two classes of open queueing network models of computer communication systems: 1) local-balanced queueing networks with multiple classes of customers and 2) the Reiser-Kobayashi diffusion approximation model. The problem of selecting optimal bandwidths for communication lines and switches and computing machinery is difficult due to 1) the economy of scale exhibited by components (i.e., the bandwidth per dollar increases with the total cost of the component) and 2) the discrete nature of computer/communication components (for instance it is possible to lease communication lines with 2400-Bd or 4800-Bd band-widths but not one with a 2401.3-Bd bandwidth). This paper develops aun algorithm to select servers taking both of these characteristics of server costs into account. The contribution of this paper is to discuss 1) the optimization of more general network models with 2) the consideration of more realistic tariffs and 3) more constraints on network behavior than were previously analyzed.