The principal investigators (PI) will develop and study new non- probabilistic models to analyze the behavior of control algorithms for resource allocation in packet switched data communications networks. Their approach to dealing with uncertainty differs from traditional approaches. Rather than specifying statistical properties of traffic they plan to employ and extend a non- probabilistic model for demand that specifies hard constraints satisfied by the traffic. The model facilitates the rigorous computation of bounds for parameters such as maximum delay, average delay, and buffering requirements in networks. They will focus on dynamic routing and flow control which involve the study of coupled queues. The use of models such as the nonprobabilistic model is likely to overcome the analytical problems traditionally encountered. They provide examples of problems that address these issues in networks using point to point and interacting broadcast links. As the size and demand for data networks grow, the economic impact of developing useful tools for engineering them will be quite significant. This approach develops some of these tools. ***//