Comparing the performance of distributed hash tables under churn

A protocol for a distributed hash table (DHT) incurs communication costs to keep up with churn – changes in membership – in order to maintain its ability to route lookups efficiently. This paper formulates a unified framework for evaluating cost and performance. Communication costs are combined into a single cost measure (bytes), and performance benefits are reduced to a single latency measure. This approach correctly accounts for background maintenance traffic and timeouts during lookup due to stale routing data, and also correctly leaves open the possibility of different preferences in the tradeoff of lookup time versus communication cost. Using the unified framework, this paper analyzes the effects of DHT parameters on the performance of four protocols under churn.