Obtaining consistent good/bad plan set in the presence of faults

Abstract

In a cooperative network, we need a mechanism that allows all correct processors to reach a common agreement. Hence, more and more attention has been drawn on the agreement related problems (Byzantine Agreement (BA) problem and Consensus problem). In previous results, the goal of BA and Consensus is obtaining a common value no matter this value is good or bad. To address this problem, Correia, Bessani and Veríssimo proposed the Byzantine Generals with Alternative Plans (BGAP) protocol that requires the common value come from the good plan set. BGAP is a graceful and practical protocol. They also pointed out that the BA problem with alternative plans is unsolvable if correct processors have different good plans and bad plans. In this paper, we propose the Plan_Consensus Protocol (PCP) to ensure that all correct processors obtain a consistent good plan set and a consistent bad plan set in the network.

A Flexible Consensus Protocol for Distributed Systems

“…The protocol can decide one of the proposed values or a default value ⊥ / ∈ V . Any protocol designed for the MVC problem shall satisfy five requirements as follows [22], [24], [26]:…”

“…Validity1: If there is a value v such that for any correct processor P i , v ∈ GP i , then any correct processor FIGURE 1. Plan_Consensus Protocol (PCP) [24].…”

“…To tackle this issue, we propose a protocol that makes all the correct processors have the same set of good plans and the same set of bad plans (to reduce Variation 4, 3 and 2 to Variation 1) [24]. This protocol is called Plan_Consensus Protocol (PCP).…”

“…1. Readers interested in understanding how the PCP works are advised to check out the reference [24].…”

“…In the Msg_Collecting Phase, each processor will store the received messages into an ECP-tree. ECP-tree is conceptually similar to ic-tree [24]. The difference between ic-tree and ECP-tree is that ic-tree starts from Level 1 and ECP-tree starts from Level 0.…”