Performance evaluation of EpiChord under high churn

Churn has a great effect on the performance of structured Peer-to-Peer (P2P) overlays -- specifically in mobile environments, where overlays have to deal with frequent join and leave events of nodes. In this paper, we evaluate the performance of EpiChord under high churn. EpiChord is a structured P2P overlay based on Chord, which uses a Distributed Hash Table (DHT) and removes the O(logN)-state-per-node restriction imposed by the majority of other DHT topologies. This is done by using a reactive routing state maintenance strategy that repays network maintenance costs into lookup queries, resulting in a significantly better lookup performance with comparable maintenance costs to traditional multi-hop DHTs. While comparative studies of overlay algorithms for wired networks have been reported, no such evaluation has been carried out of the suitability of the EpiChord overlay for mobile networks. This paper evaluates the performance and efficiency of EpiChord, taking into account the churn conditions as seen in mobile networks. The evaluation is conducted using the OverSim simulation framework. The simulation results suggest that it is feasible for mobile peers to take part in the overlay indicated by the observed results for success ratio and bandwidth consumption. We further show that a large degree of parallelism in the lookups is not substantially improving the performance, rather a parallelism degree of 3 is sufficient to make EpiChord resilient under different varied levels of churn.