Exploring large-scale peer-to-peer live streaming topologies

Abstract

Real-world live peer-to-peer (P2P) streaming applications have been successfully deployed in the Internet, delivering live multimedia content to millions of users at any given time. With relative simplicity in design with respect to peer selection and topology construction protocols and without much algorithmic sophistication, current-generation live P2P streaming applications are able to provide users with adequately satisfying viewing experiences. That said, little existing research has provided sufficient insights on the time-varying internal characteristics of peer-to-peer topologies in live streaming. This article presents Magellan, our collaborative work with UUSee Inc., Beijing, China, for exploring and charting graph theoretical properties of practical P2P streaming topologies, gaining important insights in their topological dynamics over a long period of time. With more than 120 GB worth of traces starting September 2006 from a commercially deployed P2P live streaming system that represents UUSee's core product, we have completed a thorough and in-depth investigation of the topological properties in large-scale live P2P streaming, as well as their evolutionary behavior over time, for example, at different times of the day and in flash crowd scenarios. We seek to explore real-world P2P streaming topologies with respect to their graph theoretical metrics, such as the degree, clustering coefficient, and reciprocity. In addition, we compare our findings with results from existing studies on topological properties of P2P file sharing applications, and present new and unique observations specific to streaming. We have observed that live P2P streaming sessions demonstrate excellent scalability, a high level of reciprocity, a clustering phenomenon in each ISP, and a degree distribution that does not follow the power-law distribution. © 2008 ACM.