Two New Protocols for Fault Tolerant Agreement

The paper attempts to handle failures effectively, while reaching agreement, in a distributed transaction processing system. The standard protocols such as BFTDC [3], Zyzzyva [4] and PBFT [5] handle the problem to a greater extent. However, the limitation with these protocols is that they incur increased message overhead as well as large latency. Moreover, the nodes are evacuated from the transaction system after being declared faulty. We propose a novel proactive based agreement which identifies the tentative failures in the system. To improve the failure resiliency with minimum execution overhead, we also propose an optimized reactive view change mechanism. Both mechanisms have been analyzed and compared. The dynamic analysis of the protocol reflects that, in a faulty scenario, the proactive approach is computationally more efficient with reduced latency as compared to reactive one. Moreover, unlike PBFT and BFTDC, our agreement protocol runs in two phases, which leads to reduced message overhead and total execution time. The protocol treats the fail-silent (i.e. crashed) nodes in the system.