A consensus protocol based on a weak failure detector and a sliding round window

Abstract

The paper revisits the "sliding window" notion commonly encountered in communication protocols and applies it to the round numbers of round-based asynchronous protocols. This approach is novel. To illustrate its benefits, the paper presents an original weak failure detector-based consensus protocol that allows each process to be simultaneously involved in several rounds. The rounds in which a process is simultaneously involved defines "sliding round window". The proposed approach has several advantages. It fits better to the uncertainty created by the asynchrony and failures, and consequently permits one to design efficient round-based asynchronous protocols. Maybe more important, it also provides a better understanding of the global synchronization that manages the protocol progress from round to round. This appears clearly in the proposed failure detector-based consensus protocol, where the "sliding round window" allows one to dynamically define the message exchange pattern for each round separately.