Evaluation of the Broadcast Operation in Kademlia

Several proposals exist that try to enhance Distributed Hash Table (DHT) systems with broadcasting capabilities. None of them however specifically addresses the particularities of Kademlia, an important DHT, used in well known real applications. Our work analyzes the implications of Kademlia´s use of XOR-based distance metrics and subsequently discusses the applicability of existing broadcasting proposals to it. Based on this, several algorithms for broadcasting in Kademlia have been implemented and experimentally evaluated under different conditions of churn and failure rate. All significant assessment criteria have been considered: node coverage, messages to nodes ratio, latency and imbalance factor. Since no perfect solution exists, a discussion on the choices and compromises to make depending on system characteristics or application priorities is presented. In addition, several enhancements are proposed that profit from Kademlia characteristics in order to make the broadcasting more robust against stale routing information or malfunctioning nodes.