Beyond the Design of PBFT

Abstract

In the previous chapter, we presented a simplified version of the PBFT consensus protocol. Although this simplified protocol can easily serve as the workhorse in any deployment of a per-missioned blockchain, there is still much room for improvement. In this chapter, we will take six steps to develop such improvements. First, we will formally model the performance of PBFT; then we focus on the typical implementation techniques that are applied to optimize the performance of PBFT (and of other primary-backup consensus protocols); third, we review common implementation techniques used to improve other primary-backup protocols; fourth, we explore the usage of trusted components; fifth, we consider the limitations of PBFT and other primary-backup consensus protocols and discuss techniques to deal with these limitations; and, finally, we examine how the resilience of practical consensus protocols can be further improved.