With so much media now available in electronic format, peer-to-peer (P2P) file sharing is becoming increasingly popular. From books to music, videos to data, traffic is streaming to and from users all over to globe as they strive to obtain and share information, both legally and illegally. But what impact does this trend have on the internet service provider (ISP) and who really foots the bill for the continuing increase in P2P traffic?
P2P originally emerged in 1999 with the development and release of early file-sharing applications. Since then, internet traffic has shifted from its original focus of interactive web browsing to passive P2P file sharing. The acceleration in popularity from users of both home-based PCs and mobile dongle access devices was incredibly quick. Current estimations are that around 90% of local and 60% of backbone traffic on the internet is centred on P2P.
P2P encompasses communications technology such as Skype, distributed-computing systems such as SETI and other forms of content distribution. The greatest impact on ISPs is that of content distribution, due to the nature and sizes of the files which create a need for careful traffic management by the provider to avoid bottlenecking at peak times. However, it is no simple task to understand and account for the impact of P2P traffic, with users crossing not only ISP networks but also social, political and geographical boundaries. However, a recent paper published by Northwestern University and Telefonica Research has attempted to do just that.
The paper narrows its search down to one of the most popular file-sharing programs currently in use around the world – BitTorrent. By studying BitTorrent and its users, the researchers have tried to understand how the traffic flows and how people are currently using the service. Some of their findings are not what you might have expected.
Previous research has shown that over half the traffic on ISP networks is P2P traffic and that number is increasing all the time. However, it might surprise some to know that around one third of this P2P traffic stays local. Northwestern and Telefonicas paper reveals that 32% of P2P traffic stays in its country of origin and 49% is intra-domain or only crosses to a single exterior peer link. As well as this, a large proportion of BitTorrent traffic stays within a LAN, usually run by an enterprise or hosting company, meaning this traffic never actually hits the internet backbone of the big transit providers.
To further compound the potential problems for local ISPs, the paper reveals that the majority of BitTorrent traffic is active during peak periods. Age-old myths painted BitTorrent users as night owls, hunched over their computers in the early hours of the morning seeding files or waiting for a movie to finish downloading. However, BitTorrent users appear to be active at round about the same time as every other user in the area, be they on a mobile dongle or home-based broadband.
This trend is an important factor in determining the cost to ISPs of supporting P2P traffic, because in the same way as many mobile operators used to build their networks to support the number of text messages sent on New Year’s Eve, ISPs now build their network to support the height of the peak-time traffic.
The conclusions that can be drawn from this information are that for Tier-2 providers, BitTorrent and similar P2P traffic are not adding to their costs as they don’t really deal with this traffic at all. Tier-2 providers are maximising their network for peak traffic and then selling the bandwidth wholesale to local ISPs, therefore they are actually making money from P2P traffic. For local ISPs, P2P traffic costs them money: as much as they try to pass this cost on to the consumer, the demand seems to stay ahead of the billing increases. The real fall guys in these situations are local network providers such as corporate or campus networks, who are really seeing most of this traffic and in most cases paying a significant amount for the privilege. This once again goes to show that pricing broadband in the wake of ever-increasing, changing and evolving applications is tricky to say the least and is probably best left for the market to determine.