Network Problem

Giganews Newsgroups
Subject: Network Problem
Posted by:  Ben (bjblackmo…
Date: Mon, 20 Mar 2006


We're running Windows 2003 server SP1, Exchange 2003 SP2, system is a Dell
PowerEdge 1600, 2Gb ram, 2x 160GB mirrored scsi drives, 2 NICs A= Intel Pro
1000 & B = Realtek 8139.

We had a problem on the server over the weekend (I don't think it had
anything to do with exchange). When I tried to login to OWA remotely
yesterday I got a timeout error, initially I thought our Firewall was down,
however I managed to login via VPN and everything checked out on the
firewall/vpn server. I then tried to RDC to the exchange server, but the
connection timed out. I tried to connect to our other servers, and they all
worked ok. I tried pinging the exchange server, and got no reply.

I assumed I would come in this morning to find the exchange server had
crashed or gone bang. However, it was up and running, and seemed to be fine.
I tried pinging it again from our other servers, but got no reply. I tried
pinging the other servers from the exchange server, but again, no reply. I
left the exchange server ping going (-t) and tried repairing NIC A, no
improvement, then NIC B, again no improvement. I was just about to reboot
the entire server, when I thought I'd just disable each card and see if it
would help. I disabled NIC A (intel) and noticed the ping suddenly started
to return a reply. I tried pinging several different servers and all worked
again. I then re-enabled NIC A, and pinged again, and it all worked as

I checked the event logs, and the only errors I found were DNS & NTP, which
is understandable if no traffic was getting through. There were no service
failures, no errors nothing.

What could cause both NICs to stop sending traffic, but then start again
when one is disabled?