I'm confident it's not the Mac OS X box.
If I'm logged directly into the NetBSD box and go to ftp a large file such
as Mozilla or something, I see the same behavior in the ftp progress bar.

Transfer moves along at approx 230 KB/sec for a few seconds, then...
Bzzzz, and it drops to zero for 10-15 seconds.

It only seems to happen on downloads.  Something with a large flow of
data.  Intermittent and sporadic traffic doesn't seem to be affected.

Nothing gets logged in /var/log/messages.
I suspect it might be something in the firewall config, but looking
at ipfstat doesn't show anything.

- rog

----------------------------
Date: Fri, 08 Aug 2003 14:51:39 -0700
From: Al Urbaitis <avu@lanl.gov>
To: Roger Fischer <r@aileron.org>
Subject: Re: Network traffic intermittently halts.

Roger Fischer wrote:
>
> I could use some help on ideas that might be causing my network
> throughput to intermittently halt for around 20 seconds.
>
>
open a shell to the NetBSD box, leave it open.
Create some traffic to a well known site
( ping NetBSD.org ) A few seconds worth is enough

Next time this happens go to the shell
and try pinging NetBSD.org again....

1. If the shell won't respond the problem
is between OSX and NetBSD box

2. If the shell responds but there is a big
change in response of ping most likely its
somewhere with the ISP

3. If all is reasonable with the shell then
its likely the problem is OSX ish