MERCURY: Fast Transaction Broadcast in High Performance Blockchain Systems

Blockchain systems must be secure and offer high performance. A key mechanism that these systems rely on to provide both of these features is transaction broadcast. Unfortunately, in today's systems, the broadcast protocols are highly inefficient. The wide adoption of public blockchain systems increases the importance of high performance blockchain infrastructure that offers both high throughput and low transaction confirmation latency. Underlying such infrastructures is a fast, efficient, and robust transaction broadcast mechanism.

We present Mercury, a new transaction broadcast protocol designed for high performance blockchains. Mercury shortens the transaction propagation delay using two techniques: a virtual coordinate system (VCS) and an early outburst strategy. Our simulation results show that Mercury outperforms prior propagation schemes and decreases overall propagation latency by up to 44%. When implemented in Conflux, an open-source high-throughput blockchain system, Mercury reduces transaction propagation latency by over 50% with a bandwidth overhead of less than 5%.