Network Slowdowns?

[Jamie]

Curious if anyone else has experienced this:

Network gets really slow, I've got a 100m local network connection:

xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
		[ snip ]
        media: Ethernet autoselect (100baseTX <full-duplex>)

But, when I copy files via NFS especially, but also sftp.. I get around
1-2 mbyte/sec. This is slower than the airport on a mac, claiming to be
about 1/10 the speed.

If I reboot the machine, or issue this command:

ifconfig xl0 down ; ifconfig xl0 up

Performance returns to about normal (although I still experience lockups
with NFS from time to time.. been scratching my head about that for a 
while, can't seem to find the problem)

Is there a problem with some network drivers? 

What gets freed up/reset with 'ifconfig down' that might explain why it seems
to temporarily fix the problem?




** probably unrelated, but I don't know. **

Doubt this is related, but, I found it curious:

I have also noticed when there are a lot of connections comming in and going 
out, things become unstable, making it impossible to connect to the machine 
and any existing connections "freeze".

Although the machine itself doesn't lock up, I can still access it via dumb
terminal, in these cases, even ifconfig down ; up won't restore it, however
waiting a few minutes (presumably for the conections to die) restores the 
network again. 

The second case is really hard to duplicate. I've tried establishing several
hundred connections from a local machine, but, I run out of local handles 
before I can lockup the dragonflybsd machine. (It's only happened a couple
times)

FWIW: when I did access it via dumb terminal, everything was responsive, the
load average was well under 1, so, I don't think it's being overworked.

Google suggested crappy modem/gateway to be the problem, however, as this affected
connections from the local network as well (and, in these cases, I tried adding
static routes, flushing routes, re-adding routes, etc.. just to see if it was 
related) no difference. I don't think it has anything to do with the gateway. 

During the "freeze" tcpdump reported very little traffic, when it restored itself
again, tcpdump went back to reporting more connections than the 9600baud modem
could keep up with. Lot of connect/disconnect kind of activity.


Jamie
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