Be Prepared When Network Goes Bad: An Asynchronous View-Change Protocol
This work addresses the need for efficient and reliable BFT SMR protocols in permissioned blockchain systems, particularly under varying network conditions, representing a significant advancement over existing partially synchronous and asynchronous protocols.
The paper tackles the problem of designing a Byzantine Fault Tolerant State Machine Replication (BFT SMR) protocol that is efficient under good network conditions and robust under bad ones, achieving optimal linear cost per decision under good networks and leaders, optimal quadratic cost under bad networks, while maintaining liveness.
The popularity of permissioned blockchain systems demands BFT SMR protocols that are efficient under good network conditions (synchrony) and robust under bad network conditions (asynchrony). The state-of-the-art partially synchronous BFT SMR protocols provide optimal linear communication cost per decision under synchrony and good leaders, but lose liveness under asynchrony. On the other hand, the state-of-the-art asynchronous BFT SMR protocols are live even under asynchrony, but always pay quadratic cost even under synchrony. In this paper, we propose a BFT SMR protocol that achieves the best of both worlds -- optimal linear cost per decision under good networks and leaders, optimal quadratic cost per decision under bad networks, and remains always live.