With PE1 through PE4 connected to each other via logical tunnel interfaces, the final step in building the topology is configuring the core router logical system and connecting it to all four PEs. This video covers the full core configuration and confirms connectivity is in place across the entire topology before routing protocols are added.

The core logical system connects to PE1, PE2, PE3 and PE4 via four separate logical tunnel interfaces — units 51, 52, 53, and 54 respectively, following the same naming convention established earlier in the series. Each connection gets its own IP subnet in the 10.10.x5.0/24 range, a loopback address of 5.5.5.5/32, and the core’s router ID is set to 5.5.5.5 ready for routing protocols.

Each tunnel interface is configured with an Ethernet encapsulation, an IP address, a description identifying the far-end PE, and the correct peer unit pointing to the corresponding interface on the PE side. The PE-side configurations for these core-facing interfaces are also updated in this video, completing the full mesh of logical tunnel connections across the topology.

Once all configurations are committed we have a nine-router topology — five PE devices and the core — all running within a single vMX image, fully connected at the interface level. At this stage there is no routing protocol in place so connectivity is limited to directly connected subnets, but the foundation is solid and ready for OSPF, ISIS or BGP to be layered on top.

This video marks an important milestone in the series. From this point forward all configuration work is done directly within the individual logical system CLIs rather than in the global configuration mode, making use of the set CLI logical-system command to move between virtual routers cleanly and efficiently.