A Multi-layered Model for Scalable Group Communication in P2P Overlay Networks

A group of n (>1) peers are required to cooperate with each other in distributed applications. In this paper, we consider a distributed group of multiple peers in P2P overlay networks. A P2P group is distributed, i.e. no centralized controller and is scalable and heterogeneous since various types and huge number of computers are interconnected in types of networks. In group communication, messages have to be causally delivered to every peer. In order to realize a scalable group, messages are ordered by linear time (LT) and physical time (PT) since message length is O(1). In order to use the physical time, each peer has to hold information on the accuracy of physical clock of each peer and minimum delay time among every pair of peers. Hence, the size of the information is O (n^2). In this paper, we newly discuss a multi-layered hierarchical model to reduce the size of group information. We evaluate the hierarchical model in terms of the group information size and delay time compared with a flat group model.