so if you're a torrent user living in a house with other torrent users, the following applies to you.
don't know if anyone else out there has messed with it, but about a month ago i discovered a plugin in azureus that lets peers downloading the same torrent inside a nat-enclosed unrouted lan (i.e. behind your netgear/linksys router) share data with each other at unrestricted LAN speed, creating a sort of torrent sub-network.
what does this mean to your end-users? well, in a house with multiple torrent users, if you're restricted to a single ISP and are already allowing your torrent traffic to use up the maximum available bandwidth while still allowing usability, this information is of least benefit to you- but if you choose to "team up" on torrents this way, it is not going to cost you anything performance-wise (other than the download slot in any additional user's queue), and you still have the "synergy" benefit of two clients pulling different data from the swarm and sharing with each other.
however- say one or more of your users has a laptop, and the ability to hop between open wifi networks in your neighborhood and pull data through them (using courteous bandwidth throttling, of course- don't want to strangle the golden goose)- at that point you're multihoming your torrent data, with the inconvenience being that you have to bounce back and forth between your home and remote wifi networks to share your cached data. (it helps to reannounce to the tracker whenever you reconnect to the remote network.) however- watching your throughput spike to 2mb/sec as your client shares data after leaving it running all night on the remote network is kinda fun. -grin-
one notable side effect of this is that the share ratio is pretty much, in turn, "shared" by the users of the sub-network. any time a completed piece is passed from one user to another on the sub-network, the share ratio of each user is affected rapidly. on a multihomed setup, this can over time result in an unbalanced share ratio as the user with the fastest download throughput becomes the "gateway" as its share ratio increases, resulting in better access to data in the swarm, while the rest of the clients are relegated to being "storage" as their ratio drops more and more from receiving cached data from the "gateway". this imbalance seems to require about a 1gb filesize to show up with the setup i'm currently using. of course, the data throughput of each network i'm using are important variables, so YMMV.
if you, like me, are into downloading 4-7g torrents of entire show seasons, this can be a good way to extract better performance from your existing or available resources. have fun & good night.
