Arnaud,

I would flush all your routing information on both of the AIX servers. There
could still be some routes to the old address in there and these would need
to be deleted so that the server will only use the new route. Also have you
checked the /etc/hosts files on the AIX server?

# netstat -rn

will show you your currents routes, you can either identify the old route
that is being used or flush them all by using the command

# route flush

You can then so the netstat -rn command to see the new routing table.

HIH

Steve