ncftp is not so nice

[Craig Ringer]

>>  I would expect that  the TCP/IP stack would be
>>configured such, that other applications can still get some bandwidth if 
>>they need it.

Your machine doesn't have as much control over that as you'd expect. To 
control throughput, it has to drop packets until the /remote/ host slows 
down transmission. There's no facility (alas) to say "please tranfer at 
most 10kb/s". That said, it's not uncommon to support dropping packets 
to slow down connections - though I don't know of any FTP apps that can 
do it under *nix.

You may want to look into QoS services like HTB or CBQ - see 
http://www.lartc.org/ . Using these services you can set policies on 
traffic, giving some kinds of traffic priority, rate-limiting other 
kinds, etc.

While I'd love to see a GUI config tool for linux QoS - in the style of 
iptables apps like fwbuilder - I haven't the skill to write one and have 
so far just been writing scripts as needed.

>> Such that I can still read the web or fetch mail while I'm 
>>downloading. Did the same test on Windooz XP and see the same behaviour.

> Maybe ask your ISP what is going on?  I have a 256kbps/128kbps cable
> modem and I often have several downloads going at once while reading
> mail and browsing /., all getting very good download speeds.

It'll depend a lot on how well connected you are to the sources of your 
downloads. When I use a local FTP mirror, it'll completely max my 
connection and cause behaviour somewhat similar to what has been 
described here. Admittedly it rarely gets to the point where I'm seeing 
large amounts of packet loss (since the connection should back off if 
that's happening) but I have seen it.

> Is there some type of firewall only allowing one outgoing connection at
> a time?

Not AFAIK.

Craig Ringer