Churn performance study of structured peer-to-peer overlay in supporting massively multiplayer online role playing games (MMORPGs)

In this paper, we conduct a performance study on a game scenario that supports MMORPGs through structured P2P overlay, focusing on the churn aspect - the continuous process of peer arrival and departure. Through a discrete simulation, we show that a trade-off is necessary between the game features with respect to real-time stringency, and the churn performance. For instance, in the game scenario, Map Type 1 represents a battlefield in the game world that emphasizes real-time stringent quick actions such as shooting, hence less resilient to churn; whereas Map Type 4 represents a market city in the game world that emphasizes a large group size of concurrent players at the cost of relaxed real-time stringency for actions, hence more resilient to churn. Our simulation justifies the design of the game scenario by showing that the churn performance of Map Type 1 is nearly 30% better than that of Map Type 4. Furthermore, to address the performance concerns of a global structured P2P overlay, we propose a clustered overlay setting by grouping nodes nearby into clusters. We show in the simulation that the clustered overlay setting has achieved an overall performance gain with respect to latency and churn, without incurring extra overlay maintenance cost.