Impacts of Overlay Topologies and Peer Selection on Latencies in IoT Blockchain

Abstract

The integration of blockchain with the Internet of Things (IoT) offers strong guarantees of data integrity and decentralized trust; however, latency remains a critical barrier to scalability. Under Ethereum’s default random peering, IoT deployments exhibit propagation delays ranging from 500 ms to 1000 ms, causing stale blocks and inconsistent state updates. This paper investigates the impact of peer-to-peer (P2P) overlay topologies on latency performance and introduces a lightweight peer-selection algorithm, Dual Perigee, designed to jointly optimize transaction-oriented latency (TOL) and block-oriented latency (BOL). We first develop a method to construct canonical overlay configurations (i.e., Erdős-Rényi, Barabási-Albert, and Random-Regular) and evaluate their influence on latency in a controlled IoT-blockchain environment. Experimental results reveal that static topologies fail to consistently minimize delay due to redundant message amplification and queuing effects. To address this, Dual Perigee extends the state-of-the-art Perigee algorithm by incorporating block propagation metrics into its scoring function while maintaining low computational overhead. In a 50-node Proof-of-Authority network emulated on Mininet-Wifi, Dual Perigee reduces TOL by up to 54.7% and BOL by 48.5% compared to Ethereum’s default peering, and outperforms Perigee by up to 23.4% in BOL. These findings demonstrate that latency-aware peer selection is essential for achieving responsive and scalable IoT-blockchain systems under dynamic network conditions.