Content Delivery Networks disperse content from a website over strategic global locations, allowing users to access content more quickly, while also reducing bandwidth costs and server loads. One form of CDN uses peer-to-peer (P2P) technology to achieve this goal.
Most people are familiar with peer-to-peer as it relates to illegal file sharing. Services like Napster, Grokster, and the infamous Pirate Bay, made headlines after being sued by major recording industry and movie industry corporations that claimed the file sharing services violated their copyright. Nevertheless, the technology itself is legal and very useful for practical file distribution. Numerous organizations from huge companies like AT&T to non-profit university libraries rely on P2P content distribution.
P2P itself is not one type of technology but rather refers to several types, including Gnutella, BitTorrent, and and FastTrack protocols. Content Delivery Networks can use P2P to distribute a website’s content without needing to cache the content on other dedicated servers. Instead, the users accessing the site share in the distribution of the content, without any adverse effects on their experiences.
Because a P2P CDN requires less power and hardware from the CDN service itself, many P2P CDNs offer their services for free. Websites that want to participate usually need to append the service’s URL to their content URLs or add certain code to their websites.