This paper explores the good-case latency of synchronous Byzantine Fault Tolerant (BFT) consensus protocols in the rotating leader setting. We first present a lower bound that relates the latency
of a broadcast when the sender is honest and the latency of switching to the next sender. We then
present a matching upper bound with a latency of 2∆ (∆ is the pessimistic synchronous delay) with an
optimistically responsive change to the next sender. The results imply that both our lower and upper
bounds are tight. We implement and evaluate our protocol and show that our protocol obtains similar
latency compared to state-of-the-art stable-leader protocol Sync HotStuff while allowing optimistically
responsive leader rotation.
Best paper award at OPODIS 2021: https://opodis2021.unistra.fr/