Fairly obscure Bittorrent question

[Havin_it]

'ning all,

 

I must have read a couple dozen FAQs about BT and routers/ports, but there's one thing none seem to explain. Here goes:

 

In my client (ABC) the controls for connections consist of a range of ports to use (6881-6999) and a max number of uploads (5). I've complied with the guides and forwarded ports 6881-6889 to my client PC.

 

But what ports are actually used in which direction? If I understand correctly, peers connect (to download from me) through the forwarded ports. But in that case, which ports am I downloading from? If I have 9 ports open and allow 9 upload connections, does that mean I couldn't download at all?

 

Thanks for any light you can shed on this. The docs I've seen don't give me any clue about how ports are used in BT, so it's over to you guys.

[devries]

Outgoing is your computer (all applications) talking to the internet (receiving and sending data). Incoming is the internet talking to your pc (remotely starting applications, services etcetc (receiving and sending data). If you block all incoming traffic that doesn't mean that you can't receive data :).

 

The portforwarding is only for outgoing traffic (ie your download). It has nothing to do with incoming requests (the upload). Just make sure you have disabled 'random' use of ports (or your bittorrent client ABC could use ports above the 6881-6889 range you forwarded). When you disable 'random' it means every new torrent will use port 6881, the next 6882, the next 6883 etcetc. So you could open a max of 9 torrents with this setup. (you could use more but without the portforwarding the download will be limited)

 

PS: another speed tip: limit upload speed and the number of max connections (ie the number of others allowed to download from your pc). Set it to max 4. To much connections will hinder the download.

[Havin_it]

So for each torrent, all the incoming connections (peers -> me) are sharing 1 port, is that correct?

 

I'm confused by the idea of throttling uploads though. I thought the paradigm was, the more uploading you permit, the more you can download.

[devries]

No the incoming connections use all ports (ports between ~10000-~65000). You won't notice it.

 

The paradigm sounds fine but it doesn't work that way. Reality is different :)The incoming connections distort the network connection. The more peers connecting to your pc the more distortion. Always limit it. But maybe it works different for you. Just experiment a bit :)

[adamw]

that's the way *bittorrent* is written to work (it makes download speed proportional to upload, to encourage you to share), but the problem is that if you completely saturate your outgoing bandwidth with bt upload traffic, the control signals for your downloading might find it harder to get through, and also doing anything else on the connection will get slow as heck because the bt upload traffic is hogging all the space. From a pure 'get the fastest connection' perspective, throttle uploads to maybe 50-80% of your available upload bandwidth (ask your ISP what this is). However, something else to consider is whether your ISP has a usage policy. I actually work for an ISP enforcing usage policies, and one of the big causes of high traffic is people doing huge amounts of bittorrent uploading. It's very communal spirited and all but it sure stresses out your ISPs capacity and we generally don't appreciate it a lot :). So you might want to check that out and throttle it down further if your ISP's usage department is likely to give you a friendly phone call...

[Havin_it]

Ah, I pay them extra for the privilege of no bandwidth-cap. If they start to quibble about abusing 'unlimited' usage, I'll listen, but I don't think it's gonna happen anyway.

 

So far I'm only really using BT when a new Mandrake or Knoppiix distro comes along, though I could be using it more if I knew some good sites. I came across legaltorrents.com but there ain't really much there.