Ladon: High-Performance Multi-BFT Consensus via Dynamic Global Ordering (Extended Version)

TL;DR

Ladon introduces a dynamic global ordering mechanism for Multi-BFT consensus that improves throughput and latency by allowing blocks to be ordered based on their generation time, accommodating varying block production rates.

Contribution

The paper presents Ladon, a novel Multi-BFT protocol that dynamically orders blocks across instances, overcoming performance issues of prior static global ordering methods.

Findings

Ladon-PBFT achieves approximately 8x peak throughput increase.

Ladon-HotStuff doubles the peak throughput compared to prior art.

Ladon reduces latency by about 62% in WAN deployments.

Abstract

Multi-BFT consensus runs multiple leader-based consensus instances in parallel, circumventing the leader bottleneck of a single instance. However, it contains an Achilles' heel: the need to globally order output blocks across instances. Deriving this global ordering is challenging because it must cope with different rates at which blocks are produced by instances. Prior Multi-BFT designs assign each block a global index before creation, leading to poor performance. We propose Ladon, a high-performance Multi-BFT protocol that allows varying instance block rates. Our key idea is to order blocks across instances dynamically, which eliminates blocking on slow instances. We achieve dynamic global ordering by assigning monotonic ranks to blocks. We pipeline rank coordination with the consensus process to reduce protocol overhead and combine aggregate signatures with rank information to reduce message complexity. Ladon's dynamic ordering enables blocks to be globally ordered according to their generation, which respects inter-block causality. We implemented and evaluated Ladon by integrating it with both PBFT and HotStuff protocols. Our evaluation shows that Ladon-PBFT (resp., Ladon-HotStuff) improves the peak throughput of the prior art by $\approx$8x (resp., 2x) and reduces latency by $\approx$62% (resp., 23%), when deployed with one straggling replica (out of 128 replicas) in a WAN setting.