A Churn Model Based on the Global Geographical Distribution of Nodes

The dynamics of peer participation, or churn, is critical for design, implementation and evaluation of Peer-to-peer (P2P) systems. The metrics used to characterize the churn is distributions of the node session lengths and arrival intervals. The prior studies setup the model by measuring the historical logs or records, and treat the churn as one whole black-box without understanding the inside of peer´s population. We investigate churn in another point of view, and find that modeling it based on the global geographical distribution of peer nodes will result in a system which behave in the way compliant to the measurement taken by previous works. By this model, we do see some more future things than other models. We might expect or predict when and what nodes would return back, as well as when and what nodes would disappear at high possibility. So it is useful when designing a system optimized both to the pass and the future, which could reduce the overhead of the maintenance of underlying overlay network of DHTs and lower the redundant level of replications for P2P storage system.