Stochastic Analysis and Improvement of the Reliability of DHT-Based Multicast

This paper investigates the reliability of application-level multicast based on a distributed hash table (DHT) in a highly dynamic network. Using a node residual lifetime model, we derive the stationary end-to-end delivery ratio of data streaming between a pair of nodes in the worst case, and show through numerical examples that in a practical DHT network, this ratio can be very low (e.g., less than 50%). Leveraging the property of heavy-tailed lifetime distribution, we then consider three optimizing techniques, namely senior member overlay (SMO), longer-lived neighbor selection (LNS), and reliable route selection (RRS), and present quantitative analysis of data delivery reliability under these schemes. In particular, we discuss the tradeoff between delivery ratio and the load imbalance among nodes. Simulation experiments are also used to evaluate the multicast performance under practical settings. Our model and analytic results provide useful tools for reliability analysis for other overlay-based applications (e.g., those involving persistent data transfers).