I have started my work here by familiarizing with the famous network simulator, ns-2. It seems to be a kind of de facto standard tool in academic research, even though some people try to avoid it like the plague. Yes, I think the learning curve for ns-2 really is rather steep, but there are several nice examples to get started. And I guess it's not a bad idea for the future to be able to show at least some degree of knowledge in ns-2.
At the moment I have been able to produce a simple C++ module based on the given examples. It compiles ok, but gives a mysterious 'Floating point exception' error message when I try to run it from a test Tcl script. Hmmm...