Trustworthiness among Peer Processes in Distributed Agreement Protocol

Nowadays more and more information systems are being shifted to distributed architectures because of the benefits like scalability, autonomy, and faulty-tolerance implied from the essence of the distributed systems. Here, every process is peer and cooperates with other peers to achieve common goal. In order to do that, peers have to efficiently and flexibly make an agreement on one common value which satisfies an agreement condition. In this paper, we consider a distributed group of multiple peers with no centralized coordination. We introduce a novel approach to efficiently making an agreement where each peer sends a package of multiple possible values to the other peers at each ongoing round. By exchanging multiple possible values at once, we can significantly reduce the total number of messages. The time and network resources are mostly spent in the value exchange phase. If we can reduce the time and number of messages to exchange values among peers, we can improve the efficiency of the agreement protocol. In order to efficiently exchange value packages among peers, we take advantage of the multipoint relaying mechanism to reduce the number of duplicate re-transmissions. Although we can significantly reduce the re-transmitted values, we have to realize the fault-tolerancey of the system. In addition to improving the reliability of the multipoint relaying mechanism, we newly introduce the trustworthiness among peers. By taking into account the trustworthiness of the peer, each peer broadcasts values through the trusted neighbors to the other peers. Here, the transmission fault which causes by untrusted, unreliable peers can be prevented.