P2P Caching
Content caching is a well-known and established technology used by ISPs primarily for acceleration of Web content delivery. P2P caching, similar to Web caching, temporarily stores popular content flowing into the ISP network. If the content requested by a subscriber is available from a cache, the cache satisfies the request from its temporary storage, eliminating data transfer through expensive transit line. With estimates of over 75 percent of P2P content being requested multiple times, P2P content responds well to caching, manifesting high reuse patterns.
Once a P2P cache is established, the network transparently redirects all P2P traffic to a cache, which either serves the file directly or passes the request onto a remote P2P user and simultaneously caches that file for the next user. Estimates are that P2P caches have seen an amazing 80 percent byte hit ratio, meaning that four of five files requested via P2P can be served by the cache. This is significantly much higher than hypertext transfer protocol (HTTP)/Web caching.
P2P caching is the only solution that enables ISPs to fully and affordably embrace P2P on their networks. Instead of growing bandwidth to meet increasing demand or limiting P2P usage through policies or traffic shaping, P2P caching lets ISPs simultaneously serve the needs of P2P and non-P2P users without negatively impacting either audience. In fact, P2P caching provides an improved experience for all subscribers — P2P users whose file sharing is improved through using the cache, and non-P2P users who experience better performance from networks uncongested from P2P traffic.
P2P caching enables ISPs to generate bandwidth on an as-needed basis to support peak usage without having to oversubscribe networks. P2P caching effectively manages the peaks and valleys associated with P2P usage. Most important, P2P caching saves ISPs money in bandwidth costs, limits customer support and churn costs, and prepares ISPs to take advantage of new revenue opportunities provided by P2P file sharing and distribution.
| P2P Caching | |
| Pros | Cons |
| Embraces P2P fully | Upfront investment required |
| Generates bandwidth without additional backbone investments | |
| Improved experience for P2P and non-P2P subscribers | |
