The Network Workbench: network simulation software for academic investigation of Internet concepts

Simulation offers significant advantages as a basis for academic projects in computer networking. Because many unimportant details can be abstracted away, and also because simulations can be completely repeatable, it is possible to address the same concepts more quickly than is possible with actual networks. At the same time, students who program a protocol for a network simulator come to understand the protocol much better than if they learn only from reading and lectures. This paper reports on a new network simulator, the Network Workbench, which is intended for use in the academic environment. It is based on discrete event simulation and structured around a five-layer stack abstracted from the Internet protocols (TCP/IP family). While the Workbench is less powerful than some tools used for investigation of larger networks or more complex protocols, it has compensating advantages. Its use can be learned quickly and it is sufficiently powerful, comprehensive, and extensible to allow investigation of a considerable range of problems. The Workbench, which is available to the academic community under no-cost license, includes a set of protocol programming exercises for introductory networking courses and it also has proved usable for more advanced student research projects. This paper describes the philosophy behind the workbench, gives a brief outline of its history, explains its internal structure, and describes its use in computer network teaching and research.