Performance evaluation of P2P caches: Flash-crowd case

Peer-to-peer (P2P) based content distribution networks (CDNs), e.g., BitTorrent, are widely used in the today's Internet. Since all peers interested in a specific content provide storage and upload capacity those CDNs facilitate a cheap and easy distribution of large amounts of data. However, they generate a lot of costs for Internet Service Providers (ISPs) as normal users also act as a source for downloads. One option for ISPs to encounter the problem of the costly inter-domain traffic is to establish P2P caches. In this study we investigate the potential of those caches in flash-crowd scenarios, i.e., when a large number of peers tries to download the content at the same time. To that end, we perform simulations as well as experiments with real BitTorrent clients. The evaluation shows that ISPs as well as P2P users will benefit from the use of caches.