ABSTRACT
Peer-to-peer content delivery has become one of the most popular Internet applications in recent years. Unlike conventional client/server systems, contents in a peerto-peer system are not only downloaded and consumed by users, but also generated and relayed by them; therefore, interactions among the users play an important role toward achieving e®cient sharing in such systems. In this chapter, we present a systematic measurement study to understand the peer interactions in BitTorrent, which is one of the most successful le sharing systems to date. Our measurement consists of a series of experiments, covering microscope piece-level interactions, to intra-torrent network topologies, and also inter-torrent localities. Our investigation provides abundant evidence that explains the success of BitTorrent, but also reveals signi cant limitations in its current design, thus opening possible avenues toward enhancing its performance.
