OMNeT++ :: simulation of communication networks

I have been working with products from OPNET for more than a year now. This is the first discrete event simulator that seens to approach their functionality! Check it out, free for non-commercial uses; you do want to model your home network don't you?

OMNeT Community Site

OMNeT++ is a discrete event simulation environment. Its primary application area is the simulation of communication networks, but because of its generic and flexible architecture, is successfully used in other areas like the simulation of complex IT systems, queueing networks or hardware architectures as well.