Random Network Drops on Realtek Interfaces (re)

[Cassidy Larson]

All,

I've been experiencing an intermittent issue with a drop in networking
connectivity on a couple of boxes.

At random times I drop connectivity between the servers and their
gateway. I am able to login via the secondary interface and
"/etc/netstart" and everything starts behaving as normal. My switch
shows the link is up, ifconfig shows the link is up, but I am unable
to ping my gateway until running "/etc/netstart".  Somedays it'll
happen a few times an hour, some days once every 8-10 hours. It really
is intermittent, and driving me crazy trying to track down the issue.
I've tried different cables, switches, gateways, IPs, and locations.
Memtest for 5 days showed no errors. However, the same problem exists
on two separate installs at different times.  I am able to connect to
the one server from the second via their secondary interfaces, so the
problem isn't related to both network interfaces.

Both servers have the Supermicro X7SLM-L motherboard, same CPU, RAM
and disks.  Using the Realtek network driver (re). pciconf shows:
    vendor     = 'Realtek Semiconductor'
    device     = 'Gigabit Ethernet NIC(NDIS 6.0) (RTL8168/8111)'
    class      = network
    subclass   = ethernet

I've experienced the problem for some time now on both 7.2-RELEASE and
7.2-STABLE (09/20/09) using amd64.

Any help or suggestions would be useful in getting to the bottom of this.

Thanks,

-c