Making chord go mobile

Abstract

The Chord protocol is a structured Peer-to-Peer (P2P) protocol based on distributed hash tables (DHT). By using hash keys to identify the nodes in the network and also the shared objects, it can significantly reduce the signaling overhead in a P2P overlay network, as flooding of query messages can be avoided. However, when nodes join or leave the Chord network, object references have to be rearranged in order to maintain the hash key mapping rules. This leads to high maintenance traffic, especially when nodes stay in the Chord ring only for a short time. In mobile environments, the resources and data rates of mobile devices are limited, so the maintenance traffic generated by shifting object references may cause problems when using Chord in a mobile scenario. In this work, we present a solution to the problem of frequent joins and leaves of nodes. By distinguishing static nodes and temporary nodes, we can decrease the maintenance traffic generated by shifting object references significantly.