P2P file sharing analysis for a better performance

The so-called second generation P2P file-sharing applications have with no doubt a better performance than the first implementations. The most remarkable difference is due to the file division into smaller pieces, where a receiving peer of any piece automatically becomes a new source to other peers. But a new question arises on how we distribute all the pieces provided by a seed peer to minimize the global and presumably individual download times. In this paper we summarize part of the work we have developed up until now to answer this general question, in particular, we will analyze how close the present second generation P2P file-sharing applications remain from an ideal solution with the theoretical best performance, that is, where all peers are interconnected with each other and all peers have an altruistic behavior always uploading its contents at any chance. Successive modifications of the ideal solution will lead us to more realistic scenarios. We will estimate the performance on each case and finally present the current studies we are carrying out to improve the overall capacity.