--- title: Route Redistribution into IS-IS « IS-IS Labs | daily.dev description: A hands-on lab exercise covering route redistribution into IS-IS, specifically redistributing static routes and connected subnets. The lab walks through the... canonical: https://daily.dev/posts/route-redistribution-into-is-is-is-is-labs-vwdc58f8r twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Route Redistribution into IS-IS « IS-IS Labs | daily.dev og:description: A hands-on lab exercise covering route redistribution into IS-IS, specifically redistributing static routes and connected subnets. The lab walks through the... og:url: https://daily.dev/posts/route-redistribution-into-is-is-is-is-labs-vwdc58f8r og:image: https://api.daily.dev/og/posts/VwDC58F8R.png og:image:alt: Route Redistribution into IS-IS « IS-IS Labs og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Route Redistribution into IS-IS « IS-IS Labs **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 8 min read · 0 upvotes · 0 comments ## Summary A hands-on lab exercise covering route redistribution into IS-IS, specifically redistributing static routes and connected subnets. The lab walks through the problem setup where two IS-IS routers fail to propagate external routing information, then guides configuration of redistribution into the level-2 LSP database with a high metric (3000). Key differences from OSPF are highlighted: IS-IS embeds external routes directly into router LSPs rather than using separate LSA types, which limits redistribution-induced meltdowns but increases LSP churn. Warnings about redistributing default routes (some implementations require `default-information originate`) and the risks of route redistribution causing network instability are included. Validation steps using `netlab validate` and manual routing table inspection are provided. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does IS-IS handle redistributed external routes differently from OSPF? IS-IS includes redistributed external routes directly in the router LSP, with no distinction between external and internal routes. OSPF uses separate LSA type-5 entries for external routes. This means IS-IS avoids the worst BGP-to-OSPF redistribution disasters, but every change to an external route forces the router to regenerate its LSP, increasing LSP churn. _Network engineers managing IS-IS redistribution decisions track protocol behavior comparisons like this on daily.dev._ ### Why won't FRRouting redistribute the default route into IS-IS? FRR refuses to redistribute 0.0.0.0/0 into IS-IS via standard redistribution commands. The only supported way to originate a default route in FRR's IS-IS implementation is with the `default-information originate` command, which is separate from the general redistribution configuration. _Engineers running FRRouting in production find edge cases like this faster when the IS-IS community shares them on daily.dev._ --- [View this post on daily.dev](https://daily.dev/posts/route-redistribution-into-is-is-is-is-labs-vwdc58f8r) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Route Redistribution into IS-IS « IS-IS Labs","url":"https://daily.dev/posts/route-redistribution-into-is-is-is-is-labs-vwdc58f8r","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/route-redistribution-into-is-is-is-is-labs-vwdc58f8r"},"datePublished":"2026-08-11T08:54:45.475Z","dateModified":"2026-08-11T09:21:36.924Z","description":"A hands-on lab exercise covering route redistribution into IS-IS, specifically redistributing static routes and connected subnets. 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OSPF uses separate LSA type-5 entries for external routes. This means IS-IS avoids the worst BGP-to-OSPF redistribution disasters, but every change to an external route forces the router to regenerate its LSP, increasing LSP churn. Network engineers managing IS-IS redistribution decisions track protocol behavior comparisons like this on daily.dev."}},{"@type":"Question","name":"Why won't FRRouting redistribute the default route into IS-IS?","acceptedAnswer":{"@type":"Answer","text":"FRR refuses to redistribute 0.0.0.0/0 into IS-IS via standard redistribution commands. The only supported way to originate a default route in FRR's IS-IS implementation is with the `default-information originate` command, which is separate from the general redistribution configuration. Engineers running FRRouting in production find edge cases like this faster when the IS-IS community shares them on daily.dev."}}]} ```