The Case for Servers in a Peer-to-Peer World

The increasing ease of self-expression and web-publishing has resulted in an explosion in the amount of content being generated in the current Internet. Besides traditional sources such as news portals, regular users are documenting their lives and thoughts and other people are subscribing, downloading and viewing this content. A lot of content therefore is being generated at the edge and consumed by the edge. Traditional client-server architectures are known to be in-effective in handling large correlated bursts of user demands. However, with RSS becoming more popular, such flash crowd scenarios will be more and more commonplace due to automated polling and downloads. Peer to peer protocols such as BitTorrent provide an attractive solution for such scenarios. BitTorrent networks are scalable, and the expected download time is independent of the arrival rate of peers (content consumers). However, the base performance of a BitTorrent network may not be fast enough from a user or content publisher´s perspective. Besides, BitTorrent gives poor results towards the end of a flash crowd when most of the large burst of arrivals have downloaded and left, and there are not too many peers online. We motivate the need for a content delivery network with well connected servers to participate in BitTorrent delivery streams. The servers are dynamically added and function as cushions to handle increase in demand as well as bolster a delivery stream when there is a paucity of users.