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Can't connect to all seeds? & MTU question...


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Hi all,

I was hoping someone would be able to help me with problems with seeds connecting.

My ports are forwarded correctly etc. have passed through via uPNP, etc. patched my TCPIP.sys thingy to 100, set max_halfopen to 50 etc. etc.

I believe I have pretty much set up uTorrent correctly as managed this afternoon to get a 650 kBps d/load via my 8Mb broadband via one of those slackware test torrents - so I'm assuming that's the fastest I'll manage to get it to ever go.

The thing that puzzles me is how come I can never connect to very many seeds? e.g. 14 of 51 connected (302 in swarm).

Obviously I've got my global connections set to 200 & max. connected peers per torrent at 60 as recommended via this forum.

I've tried dis/enabling DHT, uPNP, DMZ on the router etc. but all don't seem to have an effect.

Finally, that TCP optimizer suggests my MTU should be set to 1400 to avoid data breakups. Does this mean via the TCP optimizer patch, my USR (9107) router or both? My ISP recommends set the router to 1500, or 1430 if having problems. Does the computer's TCP & router MTU values have to match?

Any help would be greatly appreciated

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It's best to leave the router set to 1500 MTU. If the computer is always sending smaller MTU packets, that will never be a problem.

Your upload speed max is probably not more than a tiny fraction of your download max.

uTorrent's settings are based on max sustainable upload...which can be even LESS than upload max!

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Very much appreciated. Have raised the MTU on the router.

Why wouldn't connecting to more seeds give higher downloads? Surely the more the better?

Still getting very slow d/l speeds e.g. torrent w/332 seeds & 1219 peers giving d/l of approx. 0.4 kbps avg. 16.9 available complete torrents currently... surely I should be getting at least a healthy 60 kbps?

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A seed is probably already connected to a lot of peers -- possibly even reaching its per-torrent or global max connections, so it won't accept any more connections. The time plus speed that a seed will devote uploading to you...can be quite low. So individually, most seeds add almost nothing to your download speed UNLESS you find an extremely fast one. Or rather it finds you.

Almost everyone has the strategy of connecting to more seeds+peers...and that means they all spend a lot of bandwidth just STAYING connected and making new connections. So set max_halfopen back to 8. 50 is NOT working, as you can see!

Also, if you're connected to a lot of peers...many of them will snub you because you can't upload to all of them in a timely manner. This means the fast peers may quickly find someone else to upload to! And it is the fast peers rather than fast seeds or just lots of seeds that gives you the biggest chunk of your download speed.

"Surely I should be getting at least a healthy 60 kbps?"

Are you uploading at a healthy 60 KiloBYTES/second?

This whole system has to balance...even worse total upload has to be more than effective download speed due to losses and duplicate data.

But as low as your download speed is... (0.4 KiloBYTES/second?) I suspect either the torrent is stuck due to poisoning/fake...or your ISP is disrupting BitTorrent traffic in some way. If your upload is equally low despite having numerous peers to upload to, then it's rather likely your ISP is hostile.

What uTorrent version are you running?

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Thanks, that seems to at least make the ideas behind torrents a little clearer for me!

Anyway, have set max_halfopen to 4. Not any difference at all.

Have been getting decent upload speeds all along - averaging around 40 - 60 kBps (definately BYTES).

Have spoken to ISP, and they have stated the do not block or restrict any types of traffic whatsoever.

Also running latest uTorrent - 1.8.

Global max conn - 275

Peers max per torrent - 75

Upload slots - 6

Max upload - 85

As you can see, these are as roughly recommended by the links on this forum.

Also, have enabled/disabled all of the following to nil effect: DHT, DHT on new, uPNP (both uTorrent/router), NAT mapping, local peer discovery, peer exchange, etc.

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