DefinePK

Abstract

Byzantine fault tolerance (BFT) consensus protocols continue to be a main bottleneck for big-scale blockchain rollouts because of their natural scalability limitation. This paper presents Meta-Sharding, a new consensus protocol that solves the O(n²) communication complexity problem of standard PBFT through the use of sharding methods. This method splits the network into parallel processing shards under the control of a meta-committee, allowing near-linear scalability of throughput while keeping Byzantine fault tolerance promises. By simulations with network sizes between 50 and 1000 nodes, experimental results show that Meta-Sharding has roughly 23,000 transactions per second (TPS) at 1000 nodes, as opposed to 400-600 TPS for standard PBFT. Although Meta-Sharding suffers a bit more from latency (175ms compared to 30ms), its efficiency in processing (expressed as TPS/latency) improves exponentially to 130 TPS/ms at network sizes at which conventional PBFT is less than 20 TPS/ms. This design includes resilient fault tolerance features such as view updates and coordination of cross-shard transactions via a two-stage commit protocol. The envisioned architecture has tremendous implications for blockchain applications that demand both high transaction throughput and Byzantine fault tolerance at scale.