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Re: P2P agents for software distribution - saving the WAN from meltdown?!?
On 18 Jun 2008, at 10:42, Adrian Chadd wrote:
<random type="idea from tonight">
Automatically leeching and then seeding for long periods is trivial to set up if you can get an RSS feed with torrent enclosures. It is my (highly theoretical, naturally) understanding that many BitTorrent trackers make such feeds available.
However just because you have a fast, on-net seed for particular torrents doesn't mean that your on-net leechers will necessarily pick it up. The behaviour I have observed with BitTorrent is that clients are handed a relatively short list of potential peers by the tracker, and it's quite common for sensible, close, local peers not to be included. My assumption has been that the set of potential peers passed to the client is assembled randomly.
If this behaviour is widespread (i.e. if my observations are valid and my interpretation of those observations reasonable) then the more popular the content, the less likely leechers are to see the seed you want them to see. This relegates your local, on-net, fast seed to be a way of distributing unpopular content (that which is not being seeded by many other people).
There has been at least one presentation at NANOG in the past couple of years which describes the benefit to ISPs of p2p, by virtue of keeping traffic for popular content on-net. From memory, however, that presentation was based on a non-deployed p2p protocol which made more of an effort to help peers find local peers than the clients I described above.