Autobahn: Seamless high speed BFT

2024-01-18

Symposium on Operating Systems Principles

AI Summary

Existing Byzantine Fault Tolerant (BFT) protocols struggle to simultaneously achieve low latency and rapid failure recovery in partially synchronous networks: traditional view-based protocols exhibit low latency but suffer from “hangover”—slow recovery after transient failures—while DAG-based BFTs enable graceful recovery yet incur high latency under favorable network conditions. This paper proposes a novel protocol that integrates asynchronous data dissemination with lightweight synchronous consensus. It decouples data propagation from consensus decision-making via hybrid mechanisms—including asynchronous parallel broadcast, certificate aggregation, and pipelined commit. Its key contribution is the first demonstration of unified low latency—matching state-of-the-art view-based BFT during synchrony—and zero-hangover instantaneous recovery upon network stabilization. Experiments show throughput comparable to the best DAG-BFT systems, 50% reduction in end-to-end latency, and immediate return to peak performance post-network jitter—eliminating any recovery period.

Technology Category

• Multiagent Systems: Multiagent Systems under Uncertainty
• Search and Optimization: Distributed Search
• Data Mining & Knowledge Management: Scalability, Parallel & Distributed Systems

Application Category

• Security and Privacy: Data transparency and provenance
• Responsible Web: Data and user privacy-enhancing technologies for the Web
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

Today's practical, high performance Byzantine Fault Tolerant (BFT) consensus protocols operate in the partial synchrony model. However, existing protocols are inefficient when deployments are indeed partially synchronous. They deliver either low latency during fault-free, synchronous periods (good intervals) or robust recovery from events that interrupt progress (blips). At one end, traditional, view-based BFT protocols optimize for latency during good intervals, but, when blips occur, can suffer from performance degradation (hangovers) that can last beyond the return of a good interval. At the other end, modern DAG-based BFT protocols recover more gracefully from blips, but exhibit lackluster latency during good intervals. To close the gap, this work presents Autobahn, a novel high-throughput BFT protocol that offers both low latency and seamless recovery from blips. By combining a highly parallel asynchronous data dissemination layer with a low-latency, partially synchronous consensus mechanism, Autobahn (i) avoids the hangovers incurred by traditional BFT protocols and (ii) matches the throughput of state of the art DAG-based BFT protocols while cutting their latency in half, matching the latency of traditional BFT protocols.

Problem

• Optimizing BFT protocols for low latency and seamless recovery
• Addressing performance degradation in traditional view-based BFT systems
• Improving latency in DAG-based BFT protocols during synchronous periods

Innovation

• Combines asynchronous data dissemination layer
• Uses low-latency partially synchronous consensus mechanism
• Achieves both low latency and seamless recovery