Scalable and Robust Structured Peer-to-Peer Based on Balanced Kautz Tree

In order to improve scalability and reduce maintenance overhead for structured Peer-to-Peer (P2P) systems, researchers design optimal architectures with constant degree and logarithmical diameter. The expected topologies, however, require the number of peers to be some given values determined by the average degree and the diameter. Hence, existing designs fail to address the issue due to the fact that 1) we cannot guarantee how many peers to join a P2P system at a given time, and 2) a P2P system is typically dynamic with peers frequently coming and leaving. In this work, we propose BAKE scheme based on balanced Kautz tree structure with logdn diameter and constant degree even the number of peers is an arbitrary value. By keeping a total ordering of peers and employing a robust locality-preserved resource placement strategy, resources that are similar in single or multi-dimensional attributes space are stored on a same peer or neighboring peers. Through analysis and simulations, we show that BAKE achieves optimal diameter and good connectivity as the Kautz digraph does (almost achieves the Moore bound), and supports both exact and range queries efficiently. Indeed, the concepts of balanced Kautz tree and Kautz ring introduced in this work can also be extended and applied to other interconnection networks after minimal modifications, for example, de Bruijn digraph.