Analysis of peer-to-peer file dissemination amongst users of different upload capacities

In recent years, overlay networks have proven an effective way of disseminating a file from a single source to a group of end users via the Internet. A number of algorithms and protocols have been suggested, implemented and studied. In particular, much attention has been given to peer-to-peer (P2P) systems such as BitTorrent [2], Slurpie [10], SplitStream [1] and Bullet [5]. The key idea is that the file is divided into M parts of equal size and that a given user may download any one of these either from the server or from a peer who has previously downloaded it. More recently, a scheme based on network coding [3] has been suggested. Here, users down-load linear combinations of file parts rather than individual file parts.