The Lambda network is a high performance, single stage, packet-switched interprocessor communication network designed for a distributed memory, parallel processor computer. Its design arises from the desired network characteristics of minimizing mean and maximum packet transfer time, local routing, expandability, deadlock avoidance, and fault tolerance. The network is based on fixed degree nodes and has O(log p) mean and maximum packet transfer distances, where p is the number of processors. The routing method is detailed and schemes for expandability, deadlock avoidance, and fault tolerance are presented. The network's performance is demonstrated via computer simulation on stochastically defined problems. The network is shown to have performance superior to that of the hypercube network for reasonable size networks (≥32 processors) when similar technology and network node designs are used for both. © 1990.