Shoal: Improving DAG-BFT Latency And Robustness ...

• Main Authors: Spiegelman, Alexander, Aurn, Balaji, Gelashvili, Rati, Li, Zekun
• Format: Report
• Language: unknown
• Published: arXiv 2023
• Subjects: Distributed, Parallel, and Cluster Computing cs.DC; FOS Computer and information sciences; narwhal*
• Online Access: https://dx.doi.org/10.48550/arxiv.2306.03058; https://arxiv.org/abs/2306.03058

The Narwhal system is a state-of-the-art Byzantine fault-tolerant scalable architecture that involves constructing a directed acyclic graph (DAG) of messages among a set of validators in a Blockchain network. Bullshark is a zero-overhead consensus protocol on top of the Narwhal's DAG that can order over 100k transactions per second. Unfortunately, the high throughput of Bullshark comes with a latency price due to the DAG construction, increasing the latency compared to the state-of-the-art leader-based BFT consensus protocols. We introduce Shoal, a protocol-agnostic framework for enhancing Narwhal-based consensus. By incorporating leader reputation and pipelining support for the first time, Shoal significantly reduces latency. Moreover, the combination of properties of the DAG construction and the leader reputation mechanism enables the elimination of timeouts in all but extremely uncommon scenarios in practice, a property we name Prevalent Responsiveness" (it strictly subsumes the established and often ...