Finding Nemo-Nemo: CFT DAG-based Consensus in the WAN
2026-04-10 • Distributed, Parallel, and Cluster Computing
Distributed, Parallel, and Cluster Computing
AI summaryⓘ
The authors present Nemo-Nemo, a new consensus protocol designed to be fault-tolerant and faster in wide-area networks. They use a special way of organizing commands called a causally ordered DAG, allowing multiple leaders to propose commands and avoid slowing down the system. Their design separates how commands spread from how agreement is reached, so the system keeps working well even with network delays. Nemo-Nemo can finalize decisions quickly, matching fast existing systems while handling more commands at once.
Crash-Fault Tolerance (CFT)Byzantine Fault Tolerance (BFT)Consensus ProtocolCausally Ordered DAGMulti-Leader ArchitectureWide-Area NetworksNetwork LatencyCommand DisseminationThroughputLeader Proposal
Authors
Rithwik Kerur, Pasindu Tennage, Philipp Jovanovic, Dahlia Malkhi, Alberto Sonnino, Igor Zablotchi
Abstract
This paper introduces Nemo-Nemo, a practical crash-fault tolerant (CFT) consensus protocol designed to outperform existing protocols in wide-area networks by bridging design principles from the CFT and Byzantine-fault tolerant (BFT) worlds. By structuring command propagation through a causally ordered DAG, Nemo-Nemo allows all consensus replicas to propose commands with a naturally self-regulating communication regime. By exploiting multi-leader architecture, Nemo-Nemo avoids the performance bottleneck inherent to single-leader protocols. By separating command dissemination from consensus logic, Nemo-Nemo handles challenging network conditions even when consensus commits are stalled. Moreover, leader proposals that miss a deadline are never dropped, but deterministically deferred and executed later, preserving throughput under transient network delays. And by enabling Nemo-Nemo to commit on a DAG in just two network hops, it matches the latency of existing CFT systems, while achieving significantly higher throughput. The result is a robust, deployable system: the first DAG-based CFT consensus protocol proven to exceed state-of-the-art wide-area network performance in both speed and resilience.