Poster

With the success of blockchains and cryptocurrencies, Byzantine Fault Tolerant state machine replication protocols have attracted considerable interest. A class of such protocols that is particularly popular are leader-based protocols, where one server (the leader) is tasked with proposing and broadcasting blocks of new data to be applied to the state machine. Simple implementation of the broadcast requires the leader to send entire blocks to all other servers, creating a network bottleneck at the leader and reducing the system throughput as the number of servers scales. We demonstrate this effect by benchmarking HotStuff, a popular leader-based protocol, and then propose a mitigation based on coding. The key idea is to let the leader encode the block into small chunks, and task each server with broadcasting a chunk, thus utilizing the bandwidth of all servers during the process. We apply this idea on HotStuff, and demonstrate a 64% improvement in throughput in a deployment across 9 servers.