Recent studies have suggested that the stability of peer-to-peer networks mayrely on persistent peers, who dwell on the network after they obtain the entirefile. In the absence of such peers, one piece becomes extremely rare in thenetwork, which leads to instability. Technological developments, however, arepoised to reduce the incidence of persistent peers, giving rise to a need for aprotocol that guarantees stability with non-persistent peers. We propose anovel peer-to-peer protocol, the group suppression protocol, to ensure thestability of peer-to-peer networks under the scenario that all the peers adoptnon-persistent behavior. Using a suitable Lyapunov potential function, thegroup suppression protocol is proven to be stable when the file is broken intotwo pieces, and detailed experiments demonstrate the stability of the protocolfor arbitrary number of pieces. We define and simulate a decentralized versionof this protocol for practical applications. Straightforward incorporation ofthe group suppression protocol into BitTorrent while retaining most ofBitTorrent's core mechanisms is also presented. Subsequent simulations showthat under certain assumptions, BitTorrent with the official protocol cannotescape from the missing piece syndrome, but BitTorrent with group suppressiondoes.
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