FreeBSD 4.11 router problems using Compaq NC3131

[jshamlet at comcast.net]

Guys,
I recently decided I'd like to replace my current FreeBSD based Internet gateway router/firewall with something a little less loud / large. I decided to go with an old FlexATX Pentium III based mainboard, and a Compaq NC3131 dual port 10/100 ethernet adapter.

Specifically, I am using an ECS P6IWP-Fe rev 2 mainboard with a Pentium III 850/100 processor, 256MB of RAM, and a Toshiba/IBM 2.5" HDD. This board has an onboard RealTek 8139 10/100 adapter that, ironically, doesn't seem to have any problems.

The only other hardware onboard is the Compaq NC3131 dual 10/100 adapter, and a USB to serial converter.

The problem is that packets seem to "hiccup" all the time. The actual data rate is fine, but the packet stream will "pause" for nearly a second, then continue. This is most apparent during shell access (either xterm or ssh). Characters will stop showing up, then stream out quickly once the system "catches up". When running top, the affect appears as tearing.

Other protocols have the same problem. Web pages will pause momentarily during loading, then almost snap in. The affect is very "jerky".

There are no errors showing up in the log, and the problem seems to come and go frequently. (the interface will work fine for a few seconds, start jerking for a few seconds, then go back to normal for a few seconds).

I also tried running the local interface through the rl0 interface, and the jerkiness went away. I'm almost tempted to just drop a 3Com 3c905TX in, and use the RealTek interface as the WAN port. I know that the RealTek chips have a poor reputation, but so far it is working much better than the fxp ports!

FYI - I attempted to run 5.3-REL, and the problem appears to go away. I would be tempted to just run 5.3, except that I have had stability problems with it, even after turning ACPI support off.

Lastly, I tried using the board both with and without using the link0 option on the ports.

Any idea what is going on?

Thanks,
Seth Henry