ISPs & P2P, Getting Along Without Getting Cozy
penguin-geek writes "Researchers at Northwestern University have discovered a way to ease the tension between ISPs and P2P users. As we all know, there's been a growing tension between Internet Service Providers (ISPs) and their customers' P2P file-sharing services, and this has driven service providers to forcefully reduce P2P traffic at the expense of unhappy subscribers and the risk of government investigations. Recently, some ISPs have tried to fix the problem through partnerships with certain P2P applications. The Ono project represents an alternative solution: a software service that allows P2P clients to efficiently identify nearby peers, without requiring any kind of cozy relationship between ISPs and P2P users. Using results collected from over 150,000 users, they have found that their system locates peers along paths that have two orders of magnitude lower latency and 30% lower loss rates than those picked at random by BitTorrent, and that these high-quality paths can lead to significant improvements in transfer rates. In challenged settings where peers are overloaded in terms of available bandwidth, Ono provides a 31% average download-rate improvement; in environments with large available bandwidth, Ono increases download rates by 207% on average (and improves median rates by 883%). Ono is available as a plugin for the Azureus BitTorrent client, an open tracker and an standalone service you can integrate into any P2P system."
Distribution could be wildly efficient if the users and the network operators were on the "same team." If they wanted to, they could design a bit-torrent variant where chunks are cached by intermediary servers, so that they can always be delivered quickly from a local node. Further, servers could maintain accurate models of network topology, and clients could then use this data to pick the best path. Chunks from popular files would almost always be available from a nearby server cache or a nearby peer.
The problem is that the network is either indifferent to user activities, or actively trying to prevent user activities (throttling, etc.). The end result is that the protocol is tweaked not for efficiency, but for circumvention (e.g. encryption).
I like the idea presented in the summary, since it is in principle a net benefit to both the users and the network operators. However even if it works, it may not last. For instance, ISPs may use even more aggressive tricks (maybe even exploiting this proposed variant), forcing the protocol to become even more inefficient (e.g. switching to a multi-hop TOR-like protocol).
ISPs care about money - buying more upstream costs money, and upgrading peering links or internal distribution networks costs money. They also care about customer perceived performance, and if P2P uses their networks inefficiently, and swamps a neighborhood's upstream in ways that interfere with TCP performance, that's bad. For the most part, this technology will reduce their costs by reducing exterior bandwidth, and that's good, as long as it doesn't do it in ways that the improved P2P performance finds other bottlenecks in their system to step on. The better the P2P paths can match the structure of the ISP, the lower the impact on their network will be.
This approach doesn't actually require the ISP to install anything, or to do anything, or expose them to participating-in-P2P-themselves infringement conflicts; there are other approaches that do, such as putting P2P caching servers in their network. So it's pretty much all gravy for them, especially since they know that some large fraction of the bits they're carrying are P2P. (The Akamai caching servers here aren't being used to cache the P2P - they're web caches used by traditional content providers, and what this tool is doing is using their location to identify some of the structure of the ISP network to do better P2P peer matching.)
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks