International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / In recent years the extension of interactive simulation technology to involve simulators and live vehicles from geographically dispersed sites has produced a demand for high-bandwidth communication networks that can provide guaranteed quality of service (e.g., insured availability of bandwidth and upper bounds on end-to-end delay). This paper reviews the requirements distributed interactive simulation places on the communications infrastructure and describes the Defense Simulation Internet (DSI), a network developed by the Advanced Research Projects Agency to support distributed interactive simulations. Key features of the DSI are: more than 120 participating sites spanning Europe, the United States and Asia; use of a resource reservation mechanism to provide guaranteed quality of service; and support for communication between classified sites. Furthermore, the paper describes the internetworking protocols used in the DSI to provide guaranteed quality of service and to support transmission of classified communications. Other topics discussed in the paper are research efforts that anticipate increased load on the DSI and the relevance of the technology to the integration of the telemetry range and distributed interactive simulations.