A demerit point strategy to reduce free-riding in BitTorrent

BitTorrent is one of the popular P2P protocols to share files. In contrast to a traditional client-server application, all peers in a BitTorrent network participate in both downloading and uploading. Free-riding occurs when a peer intentionally tries to avoid uploading, but still downloads from the rest of the peers. Such a free-riding peer, or free-rider, hurts the overall system to its own benefit. Though there are mechanisms to discourage free-riding in the BitTorrent protocol, the protocol can be exploited by free-riders. In this paper we propose an alternative strategy called the demerit point strategy as an extension to what the protocol already offers, and show through experimental evidence that this strategy is highly effective in mitigating free-riding. We compare the new strategy against a similar recent extension, and through experimental evidence, establish that our strategy is better. (C) 2013 Elsevier B.V. All rights reserved.