# Lab: Hide Transit Subnets in IS-IS Networks

DevFeed: [Lab: Hide Transit Subnets in IS-IS Networks](<https://devfeed.tech/articles/lab-hide-transit-subnets-in-is-is-networks-11259.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/10/isis-lab-hide-transit/>)

Published: 2025-10-17T05:46:00Z

Content type: tutorial

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [IS-IS](<https://devfeed.tech/topics/is-is.md>), [Networks](<https://devfeed.tech/topics/networks.md>), [IP routing](<https://devfeed.tech/topics/ip-routing.md>)

Tags: [browser](<https://devfeed.tech/tags/browser.md>), [github](<https://devfeed.tech/tags/github.md>), [ipv4](<https://devfeed.tech/tags/ipv4.md>), [ipv6](<https://devfeed.tech/tags/ipv6.md>), [is-is](<https://devfeed.tech/tags/is-is.md>), [netlab](<https://devfeed.tech/tags/netlab.md>), [networks](<https://devfeed.tech/tags/networks.md>), [ospf](<https://devfeed.tech/tags/ospf.md>)

## AI overview

A lab exercise demonstrates how to configure IS-IS to exclude IPv4 and IPv6 transit-link subnets from router PDUs and network-wide IP routing tables. The lab can be run with a supported device, GitHub Codespaces, or self-managed infrastructure using netlab.

## Source excerpt

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. Read more ...