Setup:
- R1 functions as the internet.
- R2 is the first location with Public IP 1.1.1.2/30
- R3 is the second location with Public IP 1.1.2.2/30
There must be a GRE tunnel configured between R2 and R3 so that OSPF can be used between them. In the example we will use a tunnel with and without IPsec.
Configuration without IPsec:
ROUTER 2:
R2: # WAN ADDRESS interface FastEthernet0/0 ip address 1.1.1.2 255.255.255.0 duplex auto speed auto ! # TUNNEL ADDRESS interface Tunnel0 ip address 10.10.10.1 255.255.255.252 tunnel source 1.1.1.2 tunnel destination 1.1.2.2 ! # LAN ADDRESS interface Loopback0 ip address 192.168.10.1 255.255.255.0 ! # OSPF CONFIG router ospf 1 log-adjacency-changes network 10.10.10.0 0.0.0.3 area 0 network 192.168.10.0 0.0.0.255 area 0 ! # DEFAULT ROUTE (TRAFFIC TOWARDS R3) ip route 0.0.0.0 0.0.0.0 1.1.1.1