In the past few years numerous peer to peer file sharing, or more generally content distribution, systems have been designed, imple-mented, and evaluated via simulations, real world measurements, and mathematical analysis. Yet, only a few of them have stood the test of time and gained wide user acceptance. BitTorrent is not just one such system; it holds the lion’s share among them. The reasons behind its success have been studied to a great extent with interesting results. Nevertheless, even though peer to peer content distribution remains one of the most active research areas, little progress has been made towards the study of the BitTorrent pro-tocol, and its possible variations, in a fully controllable but realistic simulation environme...