Here is a concrete example. Do you think this could be useful? http://www.omnest.com/webdemo/Preload_INETDEMO2006e.html

Hi, I would advise to try OMNeT++ it is widely used at various universities. The source code is open, and you can use it for free for non-profit and academic purposes. You can make it as simple, or as complicated as you like. Simulations can be explored live, and there is a useful animation and sequence chart feature that will make complex processes easier to communicate and understand. some links to look at: www.omnetpp.org main community page. This walkthrough of the INET Framework might actually be useful: http://www.omnetpp.org/doc/INET/walkthrough/tutorial.html To get a feel for the whole thing, I suggest you check out some of the videos (for example, the one titled "Using the IDE" from here: http://www.omnest.com/web-demos.php Or get some working demos (still the old version, but the idea is the same) from here: http://www.omnest.com/download-demosim.php I hope that helps.