Evaluation of network impact of content distribution mechanisms

Efficient large-scale content distribution continues to be an important problem, due to the increasing popularity of multimedia content and wide-spread use of peer-to-peer file sharing. In this paper, we evaluate the impact of different content distribution mechanisms on the network level, based on how much wide area traffic they generate. We consider traditional unicast, content distribution networks (CDN), BitTorrent, and multicast. We develop an analytical model for describing the amount of network traffic generated by the mechanisms and provide experimental results. Our results indicate that BitTorrent can be quite wasteful of network resources, whereas the traditional mechanisms have a significantly lower cost. Based on our results, we propose a series of modifications to BitTorrent which enable us to fully exploit the power of a peer-to-peer content distribution system and result in a network cost often lower than in CDNs and comparable to multicast-based distribution.