See the picture below.
The main office (LAN 10.0.1.0/24) and the branch office (LAN 10.0.2.0/24) are connected through the GRE tunnel.
The third office (10.0.3.0/24) is joined to the second branch office through IPSEC.
Is there the way to make connection between the third office and the main office through cisco 1841?
Is it possible to make routing, maybe with NAT?
In fact we need connection only with one server in the main office.
It is possible to build this setup.
the IPSEC connection between 10.0.3.x and 10.0.2.x will need to encapsulate also the traffic heading to Main office.
Steps to take:
On Main office, route the traffic towards 10.0.3.x over the GRE tunnel.
On Second Branch, add the 10.0.3.x - 10.0.1.x traffic selection to the IPSEC ACL with the Third Branch
On Third Branch, add the 10.0.3.x - 10.0.1.x traffic selection to the IPSEC ACL with the Second Branch.
Please rate if this helped.