In Link We Trust: BFT at the Speed of CFT using Switches

We introduce SwitchBFT, a novel BFT consensus protocol for data centers that matches the performance and fault tolerance guarantees of the fastest Crash Fault Tolerance (CFT) protocols. We take advantage of several unique properties of the trusted network that have emerged in modern data centers. SwitchBFT leverages packet source authentication to eliminate the overheads of cryptographic signatures, thus speeding up the fault-free scenario, and utilizes network switch programmability to enforce agreement decisions and to verify that safety is not violated, thereby offering robust performance even when some replicas are faulty. Designing a practical BFT that makes the most of these properties requires solving several challenges, such as packet losses and switch crash faults, all within the tight switch resource budget. We show that SwitchBFT outperforms state-of-the-art BFTs in scalability and performance, attaining the speed of NOPaxos, an in-switch CFT implementation.