With the topology fully built and all logical tunnel interfaces in place, this video adds OSPF to the mix — configuring OSPF area 0 between PE1, PE2, PE3, PE4 and the core router, enabling loopback advertisement across the entire domain and verifying full reachability between all virtual routers.

OSPF configuration on Juniper logical systems follows exactly the same syntax as on a standalone router — the difference is that you’re configuring it from within each logical system’s context rather than the global configuration. Using set CLI logical-system to switch between PE1, PE2, PE3, PE4 and core, we configure OSPF area 0 on each device, adding the loopback interface as passive and including all logical tunnel interfaces that carry OSPF hellos.

For each logical system the loopback interface is added to OSPF as passive — it advertises the loopback address into OSPF but doesn’t send or receive OSPF hello packets on it. The logical tunnel interfaces that connect to neighbouring virtual routers are added as active OSPF interfaces, forming the neighbour relationships that allow route exchange.

We verify the configuration step by step — checking OSPF neighbours with show ospf neighbor, confirming the state reaches Full, then checking the routing table with show route protocol ospf to confirm loopback addresses and link subnets are being learned correctly. By the time all five devices are configured and the core is added, every logical system can see every loopback and every inter-router link in the OSPF database.

The video finishes with a full connectivity test — pinging from PE1’s loopback to PE2, PE3 and PE4’s loopbacks to confirm end-to-end reachability across the virtual topology. Watching OSPF form neighbour relationships and exchange routes between nine virtual routers running inside a single vMX image makes a compelling case for just how powerful logical systems are as a study platform.

Configuration files for this stage of the build are provided for download alongside the video.