Consensus Based on Failure Detectors with a Perpetual Accuracy Property

This paper is on the Consensus problem, in the context of asynchronous distributed systems made of n processes, at most f of them may crash. A family of failure detector classes satisfying a Perpetual Accuracy property is first defined. This family includes the failure detector class S (the class of Strong failure detectors defined by Chandra and Toueg) central to the definition of a class (Sx) where x is the minimum number (x 1) of correct processes that can never be suspected to have crashed. Then, a protocol that solves the Consensus problem is given. This protocol works with any failure detector class (Sx) of this family. It is particularly simple and uses a Reliable Broadcast protocol as a skeleton. It requires n x+1 communication steps, and its communication bit complexity is (n x + 1)(n 1)jvj (where jvj is the maximal size of an initial value a process can