Monitoring, analyzing and characterizing lookup traffic in a large-scale DHT

Lookup is crucial to locate peers and resources in structured P2P networks. In this paper, we measure and analyze the traffic characteristics of lookup in Kad, which is a widely used DHT network. Some previous works studied the user behaviors of Kad, yet we believe that investigating its traffic characteristics will also be beneficial, as it gives feedbacks to fine tune the system parameters, helps to uncover the abnormalities or misuses, and provides solid ground for synthesizing P2P traffic to evaluate future designs. To track the lookup requests more efficiently and from more peers in Kad, we develop an active traffic monitor, named Rememj. From the one-week data it collected, we uncover some interesting phenomena. Moreover, we characterize the traffic characteristics from the collected data in a form that can be used for constructing representative synthetic workloads for evaluating DHT optimizations or designs. In particular, the analysis exposes heterogeneous behavior that occurs in different geographical regions (i.e., Europe, Asia, and America) or during different periods of the day. The workload measures include distribution of peers, distribution of request load, distribution of targets, as well as similarity among targets.