Agreement Problem


Several solutions were described by Lamport, Shostak and Pease in 1982. [11] They began by saying that the generals` problem can be reduced to the resolution of a “commander and lieutenant” problem, in which loyal lieutenants must act together and that their action must correspond to what the commander ordered in the event that the commander is loyal: it can be solved even in a more “realistic” problem where defective components are not interacting to attract others into an error. It is in this state of mind that practical algorithms have been developed. The Byzantine margin of error can be reached if loyal (non-defective) generals have a majority agreement on their strategy. It is possible to indicate a default voting value for missing messages. For example, missing messages may . If the agreement is that the s majority, it is possible to use a standard pre.B strategy. [11] Reliability is an important research topic in distributed computing systems, which consist of a large number of processors. To achieve reliability, it is necessary to review the error tolerance scheme of the distributed calculation system. This type of problem is known as a Byzantine agreement (BA) problem. It requires all flawless processors to agree on a common value, even if some components are damaged.

As a result, important studies on this problem of the agreement have been conducted in distributed systems. However, traditional BA protocols focus on continuously executing ⌊ (n-1) /3⌋-1 message exchange rounds, so that each flawless processor can reach an agreement. In other words, because a large number of messages result in a large protocol overload, these protocols are ineffective and inappropriate, especially for some network environments with a large number of processors. In this study, we propose a new and effective protocol to reduce the number of messages. Our protocol can collect, compare and replace the values received to find reliable processors and replace the values sent by unreliable processors. Each processor can then agree on a common value through three message exchange rounds. In addition, the proposed protocol may use the minimum number of messages to tolerate the maximum number of defective components in a distributed system. Byzantine errors are considered the most common and difficult class of errors among error modes. The Fail-Stop-Fail mode takes the simplest end of the spectrum.

While fail-stop error mode simply means that the only way to reach the defect is a node crash detected by other nodes, Byzantine errors do not involve constraints, meaning that the undone node can generate any data, including data that make it appear as a functional node. Thus, Byzantine errors can confuse error detection systems, making the margin of error more difficult. Despite the analogy, a Byzantine failure is not necessarily a security problem with hostile human interventions: it can be the result of electrical or software errors. The objective of the Byzantine margin of error is to protect against system component failures, with or without symptoms, preventing other components of the system from reaching an agreement if such an agreement is necessary for the system to function properly. The problem is complicated by the presence of insidious generals, who vote not only in favour of a suboptimal strategy, but also selectively.

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