Playing with the Bandwidth Conservation Law

We investigate performance bounds of P2P systems by application of the law of bandwidth conservation. This approach is quite general and allows us to consider various sharing systems such as fixed-rate streaming, VoD-type streaming, and elastic file sharing. Starting from a general law of bandwidth conservation, we consider several specific cases that apply to various P2P systems. For dynamic systems with a stationary arrival process, we show that simple seeding policies result in regimes where the download rates are arbitrarily fast. We consider a case with equal download rate among all peers as well as cases where the download rate is a function of upload rates, inspired by BitTorrent´s tit-for-tat policy. In particular, we show that the sustainable proportion of free-riders is closely related to the tit-for-tat parameter.