# Lab: Multilevel IS-IS Deployments

DevFeed: [Lab: Multilevel IS-IS Deployments](<https://devfeed.tech/articles/lab-multilevel-is-is-deployments-11296.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/12/multilevel-isis/>)

Published: 2025-12-12T10:45:00Z

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>), [Scalability](<https://devfeed.tech/topics/scalability.md>), [GitHub](<https://devfeed.tech/topics/github.md>), [browser](<https://devfeed.tech/topics/browser.md>)

Tags: [browser](<https://devfeed.tech/tags/browser.md>), [github](<https://devfeed.tech/tags/github.md>), [infrastructure](<https://devfeed.tech/tags/infrastructure.md>), [is-is](<https://devfeed.tech/tags/is-is.md>), [netlab](<https://devfeed.tech/tags/netlab.md>), [ospf](<https://devfeed.tech/tags/ospf.md>), [route](<https://devfeed.tech/tags/route.md>), [router](<https://devfeed.tech/tags/router.md>), [scalability](<https://devfeed.tech/tags/scalability.md>)

## AI overview

This lab tutorial explains multilevel IS-IS, including its Level 1, Level 2, and Level 1-2 router roles and its scalability relationship to OSPF areas. It directs readers to a Multilevel IS-IS Deployments lab that can be started in a browser using GitHub Codespaces or local infrastructure with netlab.

## Source excerpt

Like OSPF, IS-IS was designed when router memory was measured in megabytes and clock speeds in megahertz. Not surprisingly, it includes a scalability mechanism similar to OSPF areas. An IS-IS router could be a level-1 router (having in-area prefixes and a default route), a level-2 router (knowing just inter-area prefixes), or a level-1-2 router (equivalent to OSPF ABR). Even though multilevel IS-IS is rarely used today, it always makes sense to understand how things work, and the Multilevel IS-IS Deployments lab exercise created by Dan Partelly gives you a perfect starting point. Read more ...