Strange IP problem with 5.3 STABLE #2

[Viren Patel]

Hello. We have a Dell PE 1850 (dual Intel PRO/1000 nics,
em driver) running FreeBSD 5.3 STABLE #2. The generic
kernel has been configured to include IPFW and SMP as
follows:

   options   IPFIREWALL
   options   IPFIREWALL_VERBOSE
   options   IPDIVERT
   options   SMP

No other changes have been made. The firewall options in
rc.conf are as follows:

   firewall_enable="YES"
   firewall_type="OPEN"
   firewall_quiet="NO"

The problem is that some IP addresses on our class C
subnet do not work. I mean the NIC can be configured to
use the IP address and it shows up in ifconfig output, but
the system cannot be pinged or otherwise accessed from
outside the subnet. Within the subnet it is fine.

The only other reference I have found to a similar issue
is one involving VLANs

http://lists.freebsd.org/pipermail/freebsd-current/2004-November/042591.html

but I think my problem is different as I am not
configuring any VLANs. Also rebooting the system makes no
difference.

I had been using the RELENG_5_3 branch and run into this
problem. I switched to RELENG_5, rebuilt the system, and
the IPs that were giving me problems started working. Now,
however, I have found another one that does not work.

I am running 5_3 on other Dell and non-Dell systems but
with different network cards and have not encountered this
problem. The problem also occurs intermittently with the
GENERIC kernel. This leads me to believe the cause may be
related to Intel PRO/1000 and/or em driver.

Any help is much appreciated?

Viren

--
Viren Patel
Chemistry & Biochemistry
University of Texas at Austin