Network layout and assumptions
There are three FortiGate units acting as OSPF v2 routers on the network—Router1, Router2, and Router3. Router1 will be the designated router (DR), and Router 2 the BDR. Router3 is the area border router (ASBR) that connects to the external ISP router running BGP. Router2 has a PPPoE DSL connection that can access the Internet.
The Head Office network is connected to Router1 and Router2 on the 10.11.101.0 subnet.
Router1 and Router3 are connected over the 10.11.103.0 subnet.
Router2 and Router3 are connected over the 10.11.102.0 subnet.
The following table lists the router, interface, address, and role it is assigned.
Table 15: Routers, interfaces, and IP addresses for basic OSPF example network
Router name | Interface | IP address | Interface is connected to: |
Router1 (DR) | Internal (port1) | 10.11.101.1 | Head office network, and Router2 |
External (port2) | 10.11.102.1 | Router3 |
Router2 (BDR) | Internal (port1) | 10.11.101.2 | Head office network, and Router1 |
External (port2) | 10.11.103.2 | Router3 |
DSL (port3) | 10.12.101.2 | PPPoE DSL access |
Router3 (ASBR) | Internal1 (port1) | 10.11.102.3 | Router1 |
Internal2 (port2) | 10.11.103.3 | Router2 |
External (port3) | 172.20.120.3 | ISP’s BGP network |
Figure 110: Basic OSPF network topology
Note that other subnets can be added to the internal interfaces without changing the configuration.
