Node-Initiated Byzantine Consensus Without a Common Clock

Abstract

The majority of the literature on consensus assumes that protocols are jointly started at all nodes of the distributed system. We show how to remove this problematic assumption in semi-synchronous systems, where messages delays and relative drifts of local clocks may vary arbitrarily within known bounds. Our framework is self-stabilizing and efficient both in terms of communication and time; more concretely, compared to a synchronous start in a synchronous model of a non-self-stabilizing protocol, we achieve a constant-factor increase in the time and communicated bits to complete an instance, plus an additive communication overhead of O(n log n) broadcasted bits per time unit and node. The latter can be further reduced, at an additive increase in time complexity.