Applying distributed simulation to a communication protocol development environment

Creating robust communication protocols for distributed systems is an inherently difficult task due to the many possible executions and message orderings. We describe a communication protocol development environment based on a discrete-event simulator. We have used this development environment in testing and debugging a fault-tolerant totally-ordered multicast protocol operating over a network of multiple interconnected local-area networks (LANs). Each LAN is simulated by a processor participating in the testbed, and a “virtual gateway” mechanism is used to interconnect the LANs. The resulting distributed simulation environment allows the developer to create reproducible test scenarios, to inject faults such as network partitions, to single step protocol execution and, in general, to observe and analyze protocol behavior across each host in the network