Byzantine-Fault-Tolerant (BFT) state machine replication is an appealing technique to tolerate arbitrary failures. However, Byzantine agreement incurs a fundamental trade-off between being fast (i.e. optimal latency) and achieving optimal resilience (i.e. 2f + b +1 replicas, where f is the bound on failures and b the bound on Byzantine failures [9]). Achieving fast Byzantine replication despite f failures requires at least f + b - 2 additional replicas [10, 6, 8]. In this paper we show, perhaps surprisingly, that fast Byzantine agreement despite f failures is practically attainable using only 6-1 additional replicas, which is independent of the number of crashes tolerated. This makes our approach particularly appealing for systems that must tolerate many crashes (large f) and few Byzantine faults (small b). The core principle of our approach is to have replicas agree on a quorum of responsive replicas before agreeing on requests. This is key to circumventing the resilience lower bound of fast Byzantine agreement [6].
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机译：拜占庭式容错（BFT）状态机复制是一种吸引任意故障的吸引力。然而，Byzantine协议在快速（即最佳潜伏期）之间产生基本的权衡，并且实现最佳弹性（即2F + B +1副本，其中F是故障的绑定，B绑定拜占庭故障[9]）。尽管F故障实现快速拜占庭复制，但需要至少F + B - 2附加副本[10,6,8]。在本文中，我们令人惊讶的是，尽管F失败的快速拜占庭协议，但实际上只能使用6-1额外的副本，这与容忍的崩溃数无关。这使我们的方法特别吸引了必须容忍许多崩溃（大F）和少数拜占庭故障（小B）的系统。我们的方法的核心原则是在同意请求之前，在敏感性复制品仲裁案件上达成一致。这是避难于快速拜占庭协议的弹性的关键[6]。
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