Scamp: Peer-to-Peer Lightweight Membership Service for Large-Scale Group Communication

Gossip-based protocols have received considerable attention for broadcast applications due to their attractive scalability and reliability properties. The reliability of probabilistic gossip schemes studied so far depends on each user having knowledge of the global membership and choosing gossip targets uniformly at random. The requirement of global knowledge is undesirable in large-scale distributed systems. In this paper, we present a novel peer-to-peer membership service which operates in a completely decentralized manner in that nobody has global knowledge of membership. However, membership information is replicated robustly enough to support gossip with high reliability. Our scheme is completely self-organizing in the sense that the size of local views naturally converges to the ‘right’ value for gossip to succeed. This ‘right’ value is a function of system size, but is achieved without any node having to know the system size. We present the design, theoretical analysis and preliminary evaluation of Scamp. Simulations show that its performance is comparable to that of previous schemes which use global knowledge of membership at each node.