The dominant traffic on the internet today isn't email or web browsing, it is peer-to-peer (P2P). This is a nightmare for internet service providers (ISPs) and user organisations alike, and it's about to get worse. Legitimate business uses for P2P are starting to appear, and this will make it tricky for network managers to simply block this type of traffic.
P2P is most commonly used in software distribution, where users who have already downloaded a file then make it available for others. Such schemes also break each file into chunks, so you could download different sections from different sources simultaneously. This aggregation increases the bandwidth available, plus if one host goes offline, the file can still be downloaded from others. Popular P2P systems include BitTorrrent, eDonkey and Gnutella.
Originally used to share bootleg audio files, P2P's biggest usage is now sharing video files, especially ripped DVDs or episodes of US TV series that haven't yet been shown in the UK. But the huge size of those video files means that P2P now consumes most of the internet backbone. Stats from CacheLogic, which runs a global monitoring network called Streamsight, show that P2P overtook web browsing as the largest consumer of internet bandwidth during 2002. By the end of 2004, P2P accounted for 60 percent of all internet traffic.
Some ISPs and user organisations have applied blocks or bandwidth throttles to P2P. Hollywood and the music industry, meanwhile, have tried to close down P2P networks such as Kazaa, but the traffic simply shifted towards different networks and different P2P technologies.
But the bigger problem is that P2P is no longer just a bootlegger's tool - now it has legitimate uses, too. Already, some 10 to 20 percent of P2P traffic is compressed data and various Unix file types. The Skype IP telephone system is P2P, for example, and many software companies including Microsoft, which has a P2P system called Avalanch under development, are also looking at the technology as a potential distribution route.
It's now possible to download some Linux distributions via BitTorrent, though thus far these are mainly freeware rather than enterprise versions. The advantage is that would-be downloaders are not limited to whatever upstream bandwidth the software vendor can afford.
Network administrators have grown to hate P2P because it aggressively
consumes whatever bandwidth is available. Plus, by making things easier to
access it increases demand. And it floods the upstream bandwidth because P2P is
symmetrical whereas most broadband subscriber connections like DSL are
asymmetric, with downstream rates that are much larger than upstream.
That said, businesses can use P2P as a more resilient method of transferring
large amounts of data between multiple sites because it saves their bandwidth by
spreading the load and provides a degree of fault tolerance.
Increasingly, P2P will be too useful to block but administrators need to quickly figure out how to separate the good traffic from the bad, or they could soon find themselves swamped by unwanted data transmissions.
