Measuring the Influence of Active Measurement on Unstructured Peer-to-Peer Network

Although intensive researches have been performed regarding P2P network measurement, it is still unknown to what extent the measurement system influences the final measurement results. As an initial study, we investigated the influence of a measurement system on degree distribution of a P2P network. Theoretical analysis and simulation results suggest an interesting phase-transition phenomena when the size of the measurement system increases. A P2P network mixed with a small active measurement system remains as a scale-free network; however, the mixture P2P network will not remain as scale-free when the size of the measurement system exceeds a threshold. We also observed that the number of measuring peers usually has stronger influence than the number of connections among these peers. Briefly speaking, a small but dense active measurement is better than a large but loose measurement system.