low network speed

[Eugene M. Zheganin]

Hi.

I'm suffering from low network performance on one of my FreeBSDs.
I have an i386 8.2-RELEASE machine with an fxp(4) adapter. It's 
connected though a bunch of catalysts 2950 to another 8.2. While other 
machines in this server room using the same sequence of switches and the 
same target source server (which, btw, is equipped with an em(4) and a 
gigabit link bia catalyst 3750) show sufficient speed, this particular 
machine while using scp starts with a speed of 200 Kbytes/sec and while 
copying the file shows speed about 600-800 Kbytes/sec.

I've added this tweak to the sysctl:

net.local.stream.recvspace=196605
net.local.stream.sendspace=196605
net.inet.tcp.sendspace=196605
net.inet.tcp.recvspace=196605
net.inet.udp.recvspace=196605
kern.ipc.maxsockbuf=2621440
kern.ipc.somaxconn=4096
net.inet.tcp.sendbuf_max=524288
net.inet.tcp.recvbuf_max=524288

With these settings the copying starts at 9.5 Mbytes/sec speed, but 
then, as file is copying, drops down to 3.5 Megs/sec in about two-three 
minutes.

Is there some way to maintain 9.5 Mbytes/sec (I like this speed more) ?


Thanks.
Eugene.

P.S. This machine also runs zfs, I don't know if it's important but I 
decided to mention it.