--- title: Adjust IS-IS Timers « IS-IS Labs | daily.dev description: A hands-on lab exercise covering IS-IS timer configuration. Unlike OSPF, IS-IS allows each router to independently define its hold time, which is the key... canonical: https://daily.dev/posts/adjust-is-is-timers-is-is-labs-quhs1su5y twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Adjust IS-IS Timers « IS-IS Labs | daily.dev og:description: A hands-on lab exercise covering IS-IS timer configuration. Unlike OSPF, IS-IS allows each router to independently define its hold time, which is the key... og:url: https://daily.dev/posts/adjust-is-is-timers-is-is-labs-quhs1su5y og:image: https://api.daily.dev/og/posts/QUhs1sU5y.png og:image:alt: Adjust IS-IS Timers « 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. # Adjust IS-IS Timers « IS-IS Labs **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 5 min read · 0 upvotes · 0 comments ## Summary A hands-on lab exercise covering IS-IS timer configuration. Unlike OSPF, IS-IS allows each router to independently define its hold time, which is the key parameter for neighbor loss detection. The lab walks through reducing advertised hold times on remote routers (R1, R2) to 3 seconds and on the core router to 15 seconds, using hello-interval and hello-multiplier parameters. It also covers SPF interval, LSP generation, and CSNP generation timers and their trade-offs between convergence speed, CPU overhead, and network stability. BFD is recommended as the preferred alternative to tuning hello timers for faster failure detection. ## 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 hold time differ from OSPF hello timer negotiation between neighbors? Unlike OSPF, where hello timers must match between neighbors, IS-IS allows each router to independently define its own hold time. The advertised hold time is the only parameter relevant to neighbor loss detection — the implementation decides the hello interval and how many packets are sent within that hold time. Neighbors do not need to agree on a common value. _Network engineers tuning IS-IS deployments track protocol behavior differences like this on daily.dev._ ### What is the default IS-IS hold time and hello interval for FRRouting and Arista EOS? Most IS-IS implementations advertise a 30-second hold interval by default. FRRouting sends IIH (IS-IS Hello) packets every 3 seconds, while Arista EOS sends them every 10 seconds. The advertised hold time can be verified with 'show isis neighbors detail', which shows the 'Advertised Hold Time' field. _Engineers comparing IS-IS platform behavior across vendors find implementation-specific details like these on daily.dev._ ### What IS-IS timers can I tune to improve network convergence and what are the trade-offs? The main tunable IS-IS convergence timers are SPF interval (controls maximum time between SPF runs), LSP generation interval (controls how quickly topology changes are flooded, with too-low values risking excessive flooding from flapping interfaces), and CSNP generation interval (controls how often LSP database table-of-contents packets are sent). Lowering these improves convergence but increases CPU load and risks instability from partially updated information. _Keeping up with IS-IS and routing protocol best practices is easier when daily.dev surfaces relevant network engineering content._ ## Similar posts on daily.dev - [Crazy Delay: IOS XR OSPFv2 Default Route Origination « ipSpace.net blog](https://daily.dev/posts/crazy-delay-ios-xr-ospfv2-default-route-origination-ipspace-net-blog-t8dnomhiq) · ipSpace.net Blog · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/adjust-is-is-timers-is-is-labs-quhs1su5y) ```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":"Adjust IS-IS Timers « IS-IS Labs","url":"https://daily.dev/posts/adjust-is-is-timers-is-is-labs-quhs1su5y","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/adjust-is-is-timers-is-is-labs-quhs1su5y"},"datePublished":"2026-08-11T08:56:01.822Z","dateModified":"2026-08-11T09:29:21.709Z","description":"A hands-on lab exercise covering IS-IS timer configuration. 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