I need to make a site to site vpn between an pix and a router with duplicated subnets.
Pix as inside have a 192.168.144.0/24 and he manages already 2 site-to-site vpn, one with another pix (that have inside 10.10.9.0/24) and the second one with another pix (that have inside 10.10.12.0/24). Now i need to add another one vpn site to site with cisco ios (that have "inside" 10.10.9.0/24).
what you need to do is to perform NAT before the IPSec tunnel and translate the second 10.10.9.0/24 to some other network not yet used on the PIX, f.e. 10.10.99.0/24. The NAT configuration on the router would look like this: