Capacity of Byzantine Consensus with Capacity-Limited Point-to-Point Links

We consider the problem of maximizing the throughput of Byzantine consensus, when communication links have finite capacity. Byzantine consensus is a classical problem in distributed computing. In existing literature, the communication links are implicitly assumed to have infinite capacity. The problem changes significantly when the capacity of links is finite. We define the throughput and capacity of consensus, and identify upper bound of achievable consensus throughput. We propose an algorithm that achieves consensus capacity in complete four-node networks with at most 1 failure with arbitrary distribution of link capacities.