【Author】
Canakci, Burcu; Van Renesse, Robbert
【Source】ACM TRANSACTIONS ON COMPUTER SYSTEMS
【Abstract】Scaling Byzantine Fault Tolerant (BFT) systems in terms of membership is important for secure applications with large participation such as blockchains. While traditional protocols have low latency, they cannot handle many processors. Conversely, blockchains often have hundreds to thousands of processors to increase robustness, but they typically have high latency or energy costs. We describe various sources of unscalability in BFT consensus protocols. To improve performance, many BFT protocols optimize the normal case, where there are no failures. This can be done in a modular fashion by wrapping existing BFT protocols with a building block that we call alliance. In normal case executions, alliance can scalably determine if the initial conditions of a BFT consensus protocol predetermine the outcome, obviating running the consensus protocol. We give examples of existing protocols that solve alliance. We show that a solution based on hypercubes and MACs has desirable scalability and performance in normal case executions, with only a modest overhead otherwise. We provide important optimizations. Finally, we evaluate our solution using the ns3 simulator and show that it scales up to thousands of processors and compare with prior work in various network topologies.
【Keywords】Scalability; reliability; byzantine; consensus; blockchain; asynchronous
【摘要】根据成员资格来扩展拜占庭容错(BFT)系统对于像区块链这样有大量参与者的安全应用程序非常重要。虽然传统协议具有低延迟，但它们无法处理许多处理器。相反，区块链通常有数百到数千个处理器来提高鲁棒性，但它们通常具有较高的延迟或能源成本。我们描述了BFT共识协议中不可伸缩性的各种来源。为了提高性能，许多BFT协议优化了正常情况下没有故障的情况。这可以通过用我们称之为联盟的构件包装现有的BFT协议以模块化的方式完成。在正常的案例执行中，联盟可以可伸缩地确定BFT共识协议的初始条件是否预先确定了结果，从而避免运行共识协议。我们给出了解决联盟的现有协议的例子。我们表明，基于超立方体和MACs的解决方案在正常情况下具有理想的可伸缩性和性能，而在其他情况下只有适度的开销。我们提供重要的优化。最后，我们使用ns3模拟器对我们的解决方案进行了评估，结果表明它可以扩展到数千个处理器，并与之前在各种网络拓扑中的工作进行了比较。
【关键词】可扩展性；可靠性;拜占庭式的；共识;区块链；异步
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