Optimal asynchronous agreement and leader election algorithm for complete networks with Byzantine faulty links

Abstract

We consider agreement and leader election on asynchronous complete networks when the processors are reliable, but some of the channels are subject to failure. Fischer, Lynch, and Paterson have already shown that no deterministic algorithm can solve the agreement problem on asynchronous networks if any processor fails during the execution of the algorithm. Therefore, we consider only channel failures. The type of channel failure we consider in this paper is Byzantine failure, that is, channels fail by altering messages, sending false information, forging messages, losing messages at will, and so on. There are no restrictions on the behavior of a faulty channel. Therefore, a faulty channel may act as an adversary who forges messages on purpose to prevent the successful completion of the algorithm. Because we assume an asynchronous network, the channel delays are arbitrary. Thus, the faulty channels may not be detectable unless, for example, the faulty channels cause garbage to be sent. We present the first known agreement and leader election algorithm for asynchronous complete networks in which the processors are reliable but some channels may be Byzantine faulty. The algorithm can tolerate up to [~-~] faulty channels, where n is the number of processors in the network. We show that the bound on the number of faulty channels is optimal. When the processors terminate their corresponding algorithms, all the processors in the network will have the same correct vector, where the vector contains the private values of all the processors.

Notice of Violation of IEEE Publication Principles - A fault tolerant election protocol in asynchronous distributed systems with fail-stop model

“…Leader election is one of the fundamental problems in distributed computing [1]. The problem has been widely studied in the research community [2,3,4,5,6]. One reason for this wide interest is that many distributed protocols need an election protocol.…”

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“…The Election problem [1] requires that a unique coordinator be elected from a given set of processes. The problem has been widely studied in the research community [2,3,4,5,6] since one reason for this wide interest is that many distributed protocols need an election protocol. However, despite its usefulness, to our knowledge there is no work that has been devoted to this problem in a mobile computing environment.…”

Making asynchronous distributed computations robust to noise

“…We focus on alteration errors, in which the content of sent messages may be corrupted. Previous work in the setting of faulty channels provides fault-tolerant algorithms for several specific tasks, such as the leader election or the consensus problem (e.g., [SAA95,Sin96,GLR95,SCY98]).…”