there's a current thread on misc@ from somone with a switch that
doesn't pick up quickly when a failover trunk(4) fails over.

I just had a look at this and noticed that there's nothing sent
when this happens, the only way to notice that a machine using
has switched to another port is if it transmits a packet, or
if the fdb/mac cache times out - with certain bridges there
can be quite a delay for this to happen.

I thought that registering a callback with if_linkstatehooks
and having that send gratuitous ARP, a la carp_send_arp(), might
be a useful thing to do, but I'm a bit unsure if that's something
a layer2-like device should be doing, is there anyone who'd like
to comment?