Traffic shaping with one Ethernet?

[nigelhealy]

Hi, I want to move my torrent and file-serving from my laptop down to a plug with USB disk. I already own a Sheevaplug for file-server but am now thinking also about torrent host.
The issue I have to solve is I want the torrent traffic to use the lowest priority in my home LAN, and any other traffic (e.g. surfing) to get priority. So e.g. if Hulu watching the torrents slow down to use the remaining bandwidth.
I know Linux has traffic shaping, but can this be done with one Ethernet (so can use a sheevaplug) or does it need two Ethernets? I think it has to have 2 Ethernets.
My home LAN, I recently rewired to improve my VOIP to ensure it gets the bandwidth it needs first and all the computers come 2nd, so its  DSL modem - VOIP router - Wifi. I was thinking DSL modem - Voip - Plug - Wifi.

I also have just got a cheap 500GB USB external disk, I was thinking of that for hosting the torrent. I know it will make the Plug last longer if I get a powered USB hub but I'd prefer not.

[nigelhealy]

Thought of an idea. My VOIP router has a USB socket for plugging into laptops and XP recognizes as an Ethernet USB.
so.... can Linux do the same thing and can the Sheevaplug do Ethernet over its USB like a intel system running XP?
If so, then I can plug the USB into the WAN-facing and plug the Sheevaplug Ethernet into my LAN-facing and so be dual-NIC for traffic shaping.
Also, can the Ethernet-over-USB work with a powered USB hub - as i'd be plugging in the VOIP router's USB and an external USB harddrive into the hub and the hub into the Sheevaplug.
Currently deciding on a sheevaplug (my preference for cost and heat issue) or a Guruplug Server Plus (not my preference due to hot noisy).

[bdewacht]

The basic problem you are facing is getting an idea of the load of your network. If you have a dual ethernet, you can set it up as a router (behind your VOIP) and know it easily.

If you have a single ethernet (sheevaplug), you can attach it to a network hub (not a switch!) and use tcpdump/iptraf to get an estimate of the usage of the network (easiest is to obtain the number of packets/s).

Once you have this measure, you modify the sources of your torrent client to throttle the speed in function of the packet load. I am familiar with running / adapting qbittorrent on the plug, this should not be to hard to realize.