Sometimes you want to assign IPv4/IPv6 subnets to transit links in your network (for example, to identify interfaces in traceroute outputs), but don’t need to have those subnets in the IP routing tables throughout the whole network. Like OSPF, IS-IS has a nerd knob you can use to exclude transit subnets from the router PDUs.

Want to check how that feature works with your favorite device? Use the Hide Transit Subnets in IS-IS Networks lab exercise.

Click here to start the lab in your browser using GitHub Codespaces (or set up your own lab infrastructure). After starting the lab environment, change the directory to feature/4-hide-transit and execute netlab up.