em devices not sending proper arp packets ...

[David Kirchner]

On 11/14/05, Marc G. Fournier <scrappy at hub.org> wrote:
>
> There is a problem with the latest 4-STABLE where when you move an IP from
> one server on the network to a new one, a proper arp packet isn't being
> sent upstream, so the router isn't getting the change ...
>
> It only appears to affect the new em driver, as I have other servers on
> the network running an older kernel, where this doesn't happen ...
>
> Does anyone have a 'work around' for this?

We've had this problem too. Some have suggested turning on "portfast"
on the Cisco switches, but that doesn't resolve it. It causes severely
long delays when doing net installs (sysinstall has a very long retry
time for DNS lookups, measured in minutes). Ultimately the problem is
that the driver changed some time in the 4 branch (we think it was
between 4.1 and 4.2 or 4.2 and 4.3)

What I've heard is that because the driver was submitted by Intel,
Intel should fix the bug, and the FreeBSD team will import their fix
if they make it available.

FWIW, the driver for the same NICs included with Linux 2.6 arps OK. I
might be able to run tcpdump on a Linux box and compare it to a
FreeBSD box, and suggest where the problem is, but since the last I
heard was that we're waiting on Intel to fix it, I'm not sure if it'd
do any good?