In this article, in terms of the language queueing networks, the problem of finding the optimal values for average system response time for requests from all users for distributed information processing systems that are implemented based on the architecture "file-server", double-tier and three-tier architecture "client-server" at a fixed downtime cost, including the cost of idle users the value of the idle transmission channel, and the cost of downtime service nodes. An algorithm for solving this optimization problem is presented.

Keywords: Distributed information processing system, file-server architecture, two-level client-server architecture, three-level client-server architecture, state space, average system response time, loss cost, stationary probabilities