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.

中文翻译：

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具有非持久对等点的新型稳定点对点协议：组抑制协议

最近的研究表明，点对点网络的稳定性可能依赖于持久的对等点，他们在获得整个文件后会停留在网络上。在没有这样的对等点的情况下，一个在网络中变得极为罕见，从而导致不稳定。然而，技术发展有望减少持久对等点的发生率，从而需要一种协议来保证与非持久对等点的稳定性。我们提出了一种新颖的点对点协议，即群抑制协议，以确保在所有点都采用非持久行为的场景下点对点网络的稳定性。使用合适的李雅普诺夫势函数，当文件被分成两部分时，群抑制协议被证明是稳定的，详细的实验证明了协议对任意数量的块的稳定性。我们为实际应用定义并模拟了该协议的去中心化版本。还介绍了在保留大部分 BitTorrent 核心机制的同时，将组抑制协议直接纳入 BitTorrent。随后的模拟表明，在某些假设下，使用官方协议的 BitTorrent 无法摆脱丢失片段综合症，但具有组抑制功能的 BitTorrent 可以。