--- title: Configure IS-IS Routing for IPv4 « IS-IS Labs | daily.dev description: A hands-on lab guide for configuring IS-IS routing for IPv4 on a new router joining an existing IS-IS network. Covers the minimal configuration steps: starting... canonical: https://daily.dev/posts/configure-is-is-routing-for-ipv4-is-is-labs-c9bdmvabi twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Configure IS-IS Routing for IPv4 « IS-IS Labs | daily.dev og:description: A hands-on lab guide for configuring IS-IS routing for IPv4 on a new router joining an existing IS-IS network. Covers the minimal configuration steps: starting... og:url: https://daily.dev/posts/configure-is-is-routing-for-ipv4-is-is-labs-c9bdmvabi og:image: https://api.daily.dev/og/posts/c9bDmvaBI.png og:image:alt: Configure IS-IS Routing for IPv4 « 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. # Configure IS-IS Routing for IPv4 « IS-IS Labs **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 10 min read · 0 upvotes · 0 comments ## Summary A hands-on lab guide for configuring IS-IS routing for IPv4 on a new router joining an existing IS-IS network. Covers the minimal configuration steps: starting an IS-IS process, assigning a NET (Network Entity Title) address, enabling IS-IS on interfaces, and optionally configuring address families. Also recommends best-practice settings like point-to-point link type, Level-2-Only mode, wide metrics, and three-way handshake. Includes validation steps using FRRouting and Arista EOS command examples, plus background on IS-IS protocol origins, NSAP/NET addressing structure, and the AFI value 49 for private address space. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is a NET (Network Entity Title) in IS-IS and how is it structured? A NET is the CLNS address assigned to an IS-IS router, split into three parts: Area (leftmost bytes), System ID (6 bytes / 12 hex characters), and NSAP Selector (last byte, always 0x00 for IS-IS). It is formatted as dot-separated pairs of hex bytes, e.g. 49.0001.0000.0000.0042.00. The AFI value 49 indicates private address space, analogous to RFC 1918 for IPv4. _Network engineers working through IS-IS deployments track protocol details and lab resources like this on daily.dev._ ### What are the recommended best-practice IS-IS settings to configure beyond the minimum required? Beyond the minimum (process, NET, interface enablement), configure links with two nodes as point-to-point using 'isis network point-to-point', set the router as Level-2-Only with 'is-type level-2-only', enable wide metrics with 'metric-style wide', and on Cisco IOSv enable the IETF three-way handshake with 'isis three-way-handshake ietf'. Also enable adjacency change logging and dynamic hostname mapping. _Engineers standardizing IS-IS deployments find protocol configuration discussions like this on daily.dev._ ### Why does FRRouting show inactive IS-IS routes in the IP routing table? FRRouting uses the IP routing table as a repository for all routes, not just the best (active) ones, so it displays IS-IS routes marked as 'inactive' when they are not selected as the forwarding path. Other platforms like Arista EOS only display active IS-IS routes in the routing table, omitting the inactive ones entirely. _Developers and network engineers comparing routing platform behaviors find relevant discussions on daily.dev._ ## Similar posts on daily.dev - [Sample netlab SRv6 Lab Topologies « ipSpace.net blog](https://daily.dev/posts/sample-netlab-srv6-lab-topologies-ipspace-net-blog-s8nppf7yo) · ipSpace.net Blog · 0 upvotes · 0 comments - [The Never-Ending IPv6 Loopback Prefix Saga « ipSpace.net blog](https://daily.dev/posts/the-never-ending-ipv6-loopback-prefix-saga-ipspace-net-blog-4nlhgh10l) · ipSpace.net Blog · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/configure-is-is-routing-for-ipv4-is-is-labs-c9bdmvabi) ```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":"Configure IS-IS Routing for IPv4 « IS-IS Labs","url":"https://daily.dev/posts/configure-is-is-routing-for-ipv4-is-is-labs-c9bdmvabi","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/configure-is-is-routing-for-ipv4-is-is-labs-c9bdmvabi"},"datePublished":"2026-08-11T08:51:48.611Z","dateModified":"2026-08-11T08:52:55.521Z","description":"A hands-on lab guide for configuring IS-IS routing for IPv4 on a new router joining an existing IS-IS network. 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