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I'm halfway through a seven hour download, and I'd really like to shift the download to another machine.

I would have expected that, if I set up the second machine, it would discover the first machine is sharing the file via bittorrent, and that the two machines would sync up at LAN speeds. But when I start the second machine, it never shows up in the first machine's list of peers. Why not? Is there a way to force this?

I'm more interested in understanding how this works, than finding clever work-arounds (like copying the .torrent and data files to the other machine). I would expect them to download from other bit torrent clients, and both are set to upload at full speed.

Is there something I can change in the setup of one machine or the other to enable or force this?

I'm using uTorrent 1.5.11 on a Mac, if that matters.

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closed as off topic by joeqwerty, Sven, mailq, sysadmin1138 Nov 27 '11 at 1:20

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1 Answer 1

You need to enable LPD in torrent clients on both machines, and your router should support http://en.wikipedia.org/wiki/Multicast_address#Administratively_scoped_addresses

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uTorrent mac does not seem to have any setting for enabling this. Perhaps it is now on by default? I can find no current documentation on this. (Might be in the help file, but that's in a windows-only format). –  user102220 Nov 26 '11 at 23:27
    
But, to reiterate, I'm curious as to why this doesn't just work. There are currently only two peers for this file (I'm downloading wikipedia). When I add another machine, why don't both machines instantly see the other? They are both uploading and downloading the same file. They both see the same sources, but not each other. Why would it need LDP to find other clients, if it can find non-local clients immediately? –  user102220 Nov 26 '11 at 23:30
    
I don't use uTorrent, but for example in my Transmission it is off by default. I thing, this is because it is doing multicast noise, that my be not good for network. If your both machines are behind the same NAT, for bittorrent tracker they may be seen as single machine. If your machines use different internet ip addersses, they will try to exchange content thougt Internet, not though LAN. –  Selivanov Pavel Nov 27 '11 at 1:17
    
So, what's about file utility? –  Selivanov Pavel Nov 27 '11 at 12:10

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