P2P Caching

Most of ISP engineer know about web caching, but not all know about P2P caching. The way it work is similar like web caching, but as P2P use random port and sometime even use port 80, it's not easy to implement it in ISP environment.

To capture all the P2P traffic, P2P caching should work with Deep Packet Inspection box and redirect P2P traffic to P2P cache box. Some P2P traffic is encrypted, I'm not sure wether this kind of traffic will get advantage of P2P caching.

In P2P cache box storage and throughput is very important part. At this time, one full DVD movie in .avi format normally have 700-800MB size. You can imagine if 1000 users access the box at the same time with the speed 1 Mbps.

There are three big player for P2P caching : PeerApp, Oversi, and Cache Logic. The first two offer the product & hardware with the total investment on customer. But Cachelogic offer different way, it use revenue sharing from the bytes taken from its box.
P2P caching actually is opposite from blocking/shaping P2P traffic to save ISP's bandwidth and some argue about the license/right issue of the sharing illegal files. But from users point of view P2P caching offer faster download and from ISP point of view they can save a lot of bandwidth as well.

Other information can be seen on :
http://en.wikipedia.org/wiki/P2p_caching