I need to setup a LAN-to-LAN VPN with an outside vendor and we are both using 192.168.80.0/24 on our internal networks. On my side I have an ASA5510 and I have dealt with conflicts many times before by working with the vendors to NAT across the tunnel as needed.
In this case however, the vendor has a SonicWall Pro 1260 and he says he has no way to do the NAT on his side.
Obviously I can NAT my side of the tunnel so that the vendor sees my 192.168.80. addresses as something different than what they actually are, but don't I need the vendor to do an equivalent NAT on his side as well because I also need him to present his 192.168.80. addresses to me as something different than what they actually are as well.
So the big question is - is there any way for me to handle this completely myself (without the vendor also NATting his side) or is it impossible to do this without him also NATting his side to a network that I am not using.
Thanks for any advice.