Directed Acyclic Graph (DAG) based BFT protocols have demonstrated the capability to achieve significantly high throughput in practice. Recent advancements focused on minimizing the good-case latency of these protocols, approaching the theoretical lower bound. However, the high communication complexity inherent in existing DAG-based protocols limits their scalability. This primarily arises because each vertex in the DAG must include a linear number of edges (references) to vertices from previous rounds. We present Clownfish, a partially synchronous DAG-based BFT protocol designed to address the scalability bottleneck. Clownfish achieves lower communication complexity by selectively reducing the number of edges in DAG vertices. When using a communication-optimal consistent broadcast, Clownfish attains quadratic total communication complexity per round, outperforming prior DAG-based protocols. Clownfish also reduces the additional latency in failure cases by optimizing the round advancement rule. Additionally, Clownfish supports multiple leaders per round to reduce average latency while maintaining its lower communication complexity. Our experimental evaluation demonstrates that Clownfish provides significantly better scalability than existing DAG-based protocols.

翻译：基于有向无环图（DAG）的拜占庭容错（BFT）协议在实践中展现了实现极高吞吐量的能力。近期研究聚焦于最小化这些协议在良好情况下的延迟，已接近理论下界。然而，现有基于DAG的协议固有的高通信复杂度限制了其可扩展性。这主要源于DAG中每个顶点必须包含指向先前轮次顶点的线性数量边（引用）。我们提出小丑鱼（Clownfish），一种部分同步的基于DAG的BFT协议，旨在解决可扩展性瓶颈。小丑鱼通过选择性减少DAG顶点中的边数来实现更低的通信复杂度。当采用通信最优的一致性广播时，小丑鱼每轮达到二次方总通信复杂度，优于先前的基于DAG的协议。小丑鱼还通过优化轮次推进规则，降低了失败情况下的额外延迟。此外，小丑鱼支持每轮多个领导者，以在保持较低通信复杂度的同时降低平均延迟。我们的实验评估表明，小丑鱼相比现有基于DAG的协议提供了显著更好的可扩展性。