Analysis of the BitTorrent Protocol Modified with Fountain Code

Peer to Peer (P2P) computer networks rely on direct connections between participants instead of conventional centralized resources. These networks are useful for many purposes, but the killer application nowadays is file sharing. BitTorrent is a very popular protocol for this matter. In this paper, we use a multi-agent model of a BitTorrent network. In it, each BitTorrent client is an agent that interacts with other agents and reacts autonomously, following the same decision algorithms as real clients. Their goals are downloading contents in the shortest possible time and sharing them with other agents. The use of this multi-agent model allows us to introduce modifications to the protocol. We have modified this model to use fountain codes, also known as rate less erasure codes, a class of codes in which the original source symbols can be recovered from any subset of the encoding symbols. We evaluated how BitTorrent performs using these codes and compared with its normal behavior.