My client current config at branch office, DSL Internet with Watchguard Firewall. Trusted network configured with private ip subnet, using DHCP from the firewall. Currently communicating with Main office via VPN connection. Client has order a Point-to-Point T1 to be installed between offices and is dropping the DSL so all internet traffic will flow through the Main office. I would like to keep the firewall in place for DHCP. I now I need to add a route to the Firewall to direct traffic for the Main Office subnet through the T1 router, however, I am not sure how I configure the firewall to continue to serve as the DHCP Server but also route traffic through the Router.
Do I change the External interface on the firewall to a small subnet and assign the external ip address and T1 router ip within the subnet, i.e.
192.168.111.215 Firewall External
192.168.111.216 T1 Router
and use a another subnet for the Trusted interface, i.e.
192.168.111.1 Firewall Trusted Interface
255.255.255.128 as the subnet
and finally add the route to the main office (192.168.1.x)
Does this look right or is there a better / easier way to accomplish this?