Understanding the topologies of BitTorrent networks: A measurement view

BitTorrent (BT) is one of the most popular Peer-to-Peer (P2P) network applications. Most characteristics (except the topology) of BT network have been examined extensively by measurement approaches. In this work, we deploy a measurement system to study the performance-related properties of BT topologies. We also use our measurement system to verify some previous simulation and experiment results obtained by other researchers. Different from previous results, we observe that a BT swarm has short distance, low clustering coefficient and Gaussian-like degree-frequency distribution. This indicates that a BT swarm is very close to a random network rather than a scale-free network or a small world. We observe that the diameter of a BT network at the initial stage is small even when 95% of peers use the peer exchange extension but the networks are not fully connected at the steady stages.