Partition Detection in Byzantine Networks

TL;DR

This paper introduces NECTAR, a novel algorithm for detecting network partitions in Byzantine networks, ensuring accurate detection even with malicious nodes, and demonstrates its effectiveness through real-world experiments.

Contribution

NECTAR is the first algorithm capable of detecting network partitions in Byzantine networks without connectivity assumptions, with proven correctness and practical efficiency.

Findings

NECTAR maintains 100% accuracy in detecting partitions with Byzantine nodes.

Existing baselines' accuracy drops by at least 40% in the presence of Byzantine nodes.

NECTAR's network cost remains manageable, not exceeding around 500KB in worst cases.

Abstract

Detecting and handling network partitions is a fundamental requirement of distributed systems. Although existing partition detection methods in arbitrary graphs tolerate unreliable networks, they either assume that all nodes are correct or that a limited number of nodes might crash. In particular, Byzantine behaviors are out of the scope of these algorithms despite Byzantine fault tolerance being an active research topic for important problems such as consensus. Moreover, Byzantinetolerant protocols, such as broadcast or consensus, always rely on the assumption of connected networks. This paper addresses the problem of detecting partition in Byzantine networks (without connectivity assumption). We present a novel algorithm, which we call NECTAR, that safely detects partitioned and possibly partitionable networks and prove its correctness. NECTAR allows all correct nodes to detect whether a network could suffer from Byzantine nodes. We evaluate NECTAR's performance and compare it to two existing baselines using up to 100 nodes running real code, on various realistic topologies. Our results confirm that NECTAR maintains a 100% accuracy while the accuracy of the various existing baselines decreases by at least 40% as soon as one participant is Byzantine. Although NECTAR's network cost increases with the number of nodes and decreases with the network's diameter, it does not go above around 500KB in the worst cases.