Consistency Based Approach for Agreement Achievement among Peers

In various types of peer-to-peer (P2P) applications, peers have to so efficiently and flexibly make an agreement on one opinion that the peers can change their opinions according to the others. We discuss a flexible agreement protocol of multiple peers in a fully unstructured P2P network. In order to efficiently make an agreement, we discuss a novel approach that each peer sends a package of possible values to the other peers at each round. By taking into account the multi-value exchange scheme, we can reduce the overhead of agreement procedure, therefore increase the efficiency of the protocol. Each peer autonomously takes one of the forward, backward, mining, and observation coordination strategies to efficiently make an agreement. In the forward and backward strategies, a peer shows a new value to the other peers and backs to a previous round, respectively. In the mining one, a peer finds a tuple of previous values named a cut which satisfies the agreement condition. In the observation one, a peer does not take a new value. Some combinations of strategies, e.g. mining one and the others are inconsistent. We discuss how peers cooperate to take consistent strategies at each round.