A key performance metric in blockchains is the latency between when a transaction is broadcast and when it is confirmed (the so-called, confirmation latency). While improvements in consensus techniques can lead to lower confirmation latency, a fundamental lower bound on confirmation latency is the propagation latency of messages through the underlying peer-to-peer (p2p) network (inBitcoin, the propagation latency is several tens of seconds). The de facto p2p protocol used by Bitcoin and other blockchains is based on random connectivity: each node connects to a random subset of nodes. The induced p2p network topology can be highly suboptimal since it neglects geographical distance, differences in bandwidth, hash-power and computational abilities across peers. We present Perigee, a decentralized algorithm that automatically learns an efficient p2p topology tuned to the aforementioned network heterogeneities, purely based on peers' interactions with their neighbors. Motivated by the literature on the multi-armed bandit problem, Perigee optimally balances the tradeoff between retaining connections to known well-connected neighbors, and exploring new connections to previously-unseen neighbors. Experimental evaluations show that Perigee reduces the latency to broadcast by $33\%$. Lastly Perigee is simple, computationally lightweight, adversary-resistant, and compatible with the selfish interests of peers, making it an attractive p2p protocol for blockchains.

中文翻译：

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Perigee：区块链的高效点对点网络设计

区块链中的一个关键性能指标是交易广播和确认之间的延迟（所谓的确认延迟）。虽然共识技术的改进可以降低确认延迟，但确认延迟的基本下限是消息通过底层对等 (p2p) 网络的传播延迟（在比特币中，传播延迟为几十秒）。比特币和其他区块链使用的事实上的 p2p 协议基于随机连接：每个节点连接到节点的随机子集。诱导的 p2p 网络拓扑可能是高度次优的，因为它忽略了地理距离、带宽差异、散列能力和对等点之间的计算能力。我们呈现近地点，一种去中心化的算法，它可以自动学习一个高效的 p​​2p 拓扑，该拓扑调整到上述网络异构性，完全基于对等点与其邻居的交互。受有关多臂老虎机问题的文献的启发，Perigee 以最佳方式平衡了与已知连接良好的邻居的连接与探索与以前看不见的邻居的新连接之间的权衡。实验评估表明，Perigee 将广播延迟减少了 $33\%$。最后，Perigee 简单、计算量轻、抗攻击性强，并且与同行的自私利益兼容，使其成为区块链的有吸引力的 p2p 协议。受有关多臂老虎机问题的文献的启发，Perigee 以最佳方式平衡了与已知连接良好的邻居的连接与探索与以前看不见的邻居的新连接之间的权衡。实验评估表明，Perigee 将广播延迟减少了 $33\%$。最后，Perigee 简单、计算量轻、抗攻击性强，并且与同行的自私利益兼容，使其成为区块链的有吸引力的 p2p 协议。受有关多臂老虎机问题的文献的启发，Perigee 以最佳方式平衡了与已知连接良好的邻居的连接与探索与以前看不见的邻居的新连接之间的权衡。实验评估表明，Perigee 将广播延迟减少了 $33\%$。最后，Perigee 简单、计算量轻、抗攻击性强，并且与同行的自私利益兼容，使其成为区块链的有吸引力的 p2p 协议。