A New Stable Peer-to-Peer Protocol with Non-persistent Peers

TL;DR

This paper introduces the group suppression protocol, a new peer-to-peer system designed to maintain network stability even when all peers are non-persistent, addressing issues like the missing piece syndrome.

Contribution

The paper proposes a novel group suppression protocol that guarantees stability in non-persistent peer-to-peer networks and demonstrates its effectiveness through theoretical proofs and simulations.

Findings

Proven stability of the protocol with two-piece files.

Simulations show stability for multiple pieces.

Integration with BitTorrent reduces missing piece syndrome.

Abstract

Recent studies have suggested that the stability of peer-to-peer networks may rely on persistent peers, who dwell on the network after they obtain the entire file. In the absence of such peers, one piece becomes extremely rare in the network, which leads to instability. Technological developments, however, are poised to reduce the incidence of persistent peers, giving rise to a need for a protocol that guarantees stability with non-persistent peers. We propose a novel peer-to-peer protocol, the group suppression protocol, to ensure the stability of peer-to-peer networks under the scenario that all the peers adopt non-persistent behavior. Using a suitable Lyapunov potential function, the group suppression protocol is proven to be stable when the file is broken into two pieces, and detailed experiments demonstrate the stability of the protocol for arbitrary number of pieces. We define and simulate a decentralized version of this protocol for practical applications. Straightforward incorporation of the group suppression protocol into BitTorrent while retaining most of BitTorrent's core mechanisms is also presented. Subsequent simulations show that under certain assumptions, BitTorrent with the official protocol cannot escape from the missing piece syndrome, but BitTorrent with group suppression does.