The REAL network simulator is a network simulator designed for testing congestion and flow control mechanisms. It was written by S. Keshav . It provides users with a way of specifying such networks and to observe their behavior.
Source code is provided so that interested users can modify the simulator to their own purposes.
The simulator takes as input a scenario, which is a description of network topology, protocols, workload and control parameters. It produces as output statistics such as the number of packets sent by each source of data, the queueing delay at each queueing point, the number of dropped and retransmitted packets and other similar information. The newest version, REAL 5.0, is now available from Cornell University . Check the first link for new versions, updates etc. The PostScript versions of the user's manual and programmer's manual are also here.