Nat traffic to different subnet

Hi!

We have a partner with a Cisco Concentrator 3030, and in order to establish a IPsec conection btween us, our partner clearly stated that:
even though your local network is 192.168.2.0/24 you should NAT traffic to access our network as 172.18.31.0/24 instead.

We are supposed to access resources on 10.128.0.0/16 …
That said, the only way I would successfully establish the IPsec connection as in ‘Policies’ define src address as 172.18.31.0/24 (and dst address as 10.128.0.0/16).

Our IPsec connection is established, but I am having troubles communicating say with 10.128.16.60 …


I tried using a NAT rule with ‘Action=netmap’

chain=srcnat action=src-nat to-addresses=172.18.31.1 src-address=192.168.2.150 dst-address=10.128.16.60 
chain=dstnat action=dst-nat to-addresses=192.168.2.150 dst-address=172.18.31.1

But it doesn’t seem to work.

Would anybody help me???


Thanks in advance.