Geographic validator de- centralization in BFT consensus protocols

Abstract

Decentralization is a major constitute of blockchain technology, ensuring robustness, resilience, and trust. However, achieving true decentralization requires validators to be geographically diverse. This research focuses on the trade-offs between geographic diversity and network per- formance in blockchain systems. To address this, we developed GeoDec, an emulator designed to simulate blockchain networks under configurable geographic configurations. GeoDec supports three consensus mechanisms—HotStuff, Bullshark, and CometBFT—allowing for performance analysis across diverse network setups. GeoDec enables user to replicate validator interactions, enabling the measurement of consensus latency, throughput, and other performance metrics. To validate the emulator, we analyzed the Aptos blockchain by replicating its real-world validator distribution within GeoDec, along with other experimental cases. Results highlight the trade-offs between decentralization and per- formance: geographically concentrated validators achieve higher throughput and lower latency, while globally distributed validators enhance resilience at the cost of performance. This study provides actionable insights for blockchain developers, illustrating how geographic diversity impacts performance and offering a framework to optimize validator distribution for decentralized yet efficient networks. GeoDec serves as a valuable tool for assessing and improving the geographic decentralization of blockchain systems.