The details for each makefile target is found in tutorial.mk file.
This will do service discovery on device ER-1. One service will have missing configuration that will need to be handled.
18. Find services on device ER-1
Next up is ER-1 which does have a diff. eth3 has an mtu of 1600 which is missing in the configuration produced by NSO. This is simply because the NSO service does not set the MTU at all and rather relies on the device default of 1500.
make tutorial-sd-18-conf-diff-check-er-1
We need to address the difference in mtu between the original device configuration and what NSO produces. We are now faced with the question whether this is a mistake in the network or if it was intended. Fortunately we have the network architect by our side that informs us that it is indeed possible to configure different MTU on L3VPNs and so we know that the network device is correct.
19. Fix the missing configuration
We must add support in the NSO services to support configuring a variable MTU. The network architect tells us that only two values are allowed, the default of mtu 1500 or a higher mtu of 1600. Fortunately, a kind NSO service developer has prepared a patch set that upgrades our services to version 2 which happens to support a configurable MTU, both on the nodes/rfs layer as well as in the CFS. The find-services code is also updated.
make tutorial-sd-19-jump-to-vpn-v2
20. View differencies
Let's look at the changes in version 2.
make tutorial-sd-20-git-diff-services
21. Build service
Build and reload our packages in NSO.
make tutorial-sd-21-rebuild
22. Find services using updated service
Now let's rerun the whole config coverage and diff check on ER-1 to see if we properly read back the MTU.... and it does, yay!
make tutorial-sd-22-find-services-er-1
step22 will produce diff on /configuration/interfaces/interface{eth4}/mtu because we added default value 1500 in vrf-interface service this should be done in the cleanup phase after discovery.