Gratituous ARP and the em driver

[Nielsen]

When I change IP addresses on my 'em' gigabit NIC, ARP isn't sent 
properly. This appears to be the problem in the following bug report, 
however i'm using the 'fixed' version of the em driver (in FreeBSD 4.9).

http://www.freebsd.org/cgi/query-pr.cgi?pr=54488

Does anyone have any tips on how to get around this?

I'm building new systems with gigabit ethernet support and this problem 
keeps cropping up. I have a failover system, and when moving an IP alias 
between machines, the em NIC driver doesn't properly send out gratituous 
ARP, resulting in the IP being inaccessible.

- The problem does not occur when plugged into a 100BaseTX switch
- FreeBSD 4.9p1 / em version 1.7.16
- Tried various gigabit switches.
- One other odd thing is that when configuring the NIC (ifconfig) the 
machine locks up for several seconds.

Thanks in advance.

Nate