An OSPF area#

You will end up with OSPF exchanging routes with the other routers on your own network, advertising your LAN without forming adjacencies on it. FRR does the routing; the BGP / OSPF page writes its configuration.

Before you start#

The operator role and a licence.
The area, agreed with the other routers. Area 0 is the backbone, and a network with one area uses area 0.
A router ID: an IPv4 address that names this router. Conventionally one on a dummy interface (Adding an interface).

Step 1 — Run OSPF on the interface to your other routers#

Network → BGP / OSPF, the OSPF tab, Add an interface to OSPF: the interface that faces them, eth2, in area 0. Add interface.

Step 2 — Advertise the LAN without speaking OSPF on it#

Add interface again: the LAN, eth0, area 0, and turn on Passive. OSPF advertises the LAN's network and forms no adjacency there.

Step 3 — Set the router ID, and what else to announce#

Edit settings: the Router ID, 192.0.2.1; Redistribute static routes if your static routes should be known to the other routers; Default route Advertised when this router has one if this router is their way to the internet.

Step 4 — Let it through the firewall#

OSPF is IP protocol 89, sent to multicast addresses on each network. Allow it on the interfaces facing your routers in the input rules on Firewall.

Step 5 — Apply#

The Commit Bar lists Add interface eth2 to OSPF — Area 0, Add interface eth0 to OSPF — Area 0, passive, Set the OSPF router ID to 192.0.2.1. Apply changes.

Check it worked#

The OSPF tab's Neighbours table lists each router that formed an adjacency, with state Full. A neighbour stuck in ExStart or Exchange is almost always an MTU mismatch between the two interfaces; Init in one direction is a firewall or an area mismatch.

On Static routes, the routes learned are in the forwarding table with source OSPF.

Undoing it#

Open an interface and Remove from OSPF, or Remove OSPF for all of it; each asks once more.