If I had 2 nics in the both machines, set one up as 192.168.1.181 and the other as 24.172.***.*** and on the other machine I set the first nic up as 192.168.1.182 and the second the same as the first machine. I connect the two machines via a flip cable on the 192.168 cards and do the copying through the local cards. That way all I would have to do is swap the cable on the external card from the first machine to the second machine if the first machine went down and the IP would be the same.
errrr, I think that would work??