Peer-to-peer (P2P) file sharing systems, most notably BitTorrent (BT), have achieved tremendous success among Internet users. Although this communication paradigm does not need a dedicated server infrastructure, it is putting unprecedented traffic pressure to Internet Service Providers (ISPs) over inter-ISP links. P2P locality has therefore been examined to address this challenge. Such an approach explores the access to local resources to optimize the inter-ISP traffic. However, most of these approaches have focused on a global strategy, and attempted to change the peer selection mechanism, which potentially affect the random topology of BT and thus reduces its robustness. The content and the peer diversities are seldom discussed, particularly the video file swarms of distinct characteristics. In this paper, we for the first time examine the different BT contents and peer properties in regards to the locality issues through a large-scale measurement. We demonstrate the distinct characteristics of video file swarms, and find that the distribution of the AS clusters (a set of peers belonging to the same AS) follows the Mandelbrot-Zipf law. Our results also suggest that the peer in few ASes are more likely to form large AS clusters and most ASes on the Internet do not have enough potential for locality. Therefore, a global locality approach may not be our best choice. We then address the problem through a selective locality approach based on a novel peer prediction method.
- Video swarm