In this paper we introduce INSEE, an environment to help in the design of interconnection networks for parallel computing systems. It contains two main modules: a system to generate traffic (TrGen) and a lightweight functional simulator (FSIN). Additionally, external tools can be integrated into the environment. Examples are SICOSYS (a sophisticated network simulator that provides accurate timing information) and SIMICS (a complete, detailed computer simulator). This environment has been used to conduct some studies of interest in the design of interconnection networks, such as the effect of head-of-line blocking in the injection queues of the network routers, the effects of the injection interface in network performance, and the characteristics of topologies with skewed wraparound links.