--- title: SwiNOG 40: When a Routing Control Functions Is Too Fresh... description: A presentation from SwiNOG 40 covers a bug in Arista EOS where defining a new Routing Control Function (RCF) and applying it to BGP routing updates within the... canonical: https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: SwiNOG 40: When a Routing Control Functions Is Too Fresh « ipSpace.net blog | daily.dev og:description: A presentation from SwiNOG 40 covers a bug in Arista EOS where defining a new Routing Control Function (RCF) and applying it to BGP routing updates within the... og:url: https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol og:image: https://api.daily.dev/og/posts/AE5cpG2OL.png og:image:alt: SwiNOG 40: When a Routing Control Functions Is Too Fresh « ipSpace.net blog 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. # SwiNOG 40: When a Routing Control Functions Is Too Fresh « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 1 min read · 0 upvotes · 0 comments ## Summary A presentation from SwiNOG 40 covers a bug in Arista EOS where defining a new Routing Control Function (RCF) and applying it to BGP routing updates within the same configuration session causes unexpected behavior. The bug has since been fixed. The talk, titled 'Sorry We Messed Up,' was delivered by Stefan Funke and highlights the importance of integration testing to catch device quirks before they hit production. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What happens if you define a new Routing Control Function on Arista EOS and apply it to BGP in the same configuration session? Applying a newly defined Routing Control Function (RCF) to BGP routing updates within the same Arista EOS configuration session triggers a bug that causes unexpected behavior. The issue was publicly disclosed in a 'Sorry We Messed Up' presentation at SwiNOG 40 by Stefan Funke. The bug has since been fixed in Arista EOS. _Network engineers tracking Arista EOS quirks and BGP policy bugs find coverage like this on daily.dev._ ## Similar posts on daily.dev - [Arista cEOS Does Not Apply ACLs to Control-Plane Traffic « ipSpace.net blog](https://daily.dev/posts/arista-ceos-does-not-apply-acls-to-control-plane-traffic-ipspace-net-blog-ieh2uzhm7) · ipSpace.net Blog · 0 upvotes · 0 comments - [Switzerland built an alternative to BGP. Nobody noticed](https://daily.dev/posts/switzerland-built-an-alternative-to-bgp-nobody-noticed-9vzls8gls) · The Register · 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 - [Multivendor SR-MPLS « ipSpace.net blog](https://daily.dev/posts/multivendor-sr-mpls-ipspace-net-blog-qekokwduk) · ipSpace.net Blog · 0 upvotes · 0 comments --- Tags: [#bgp](https://daily.dev/tags/bgp) [View this post on daily.dev](https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol) ```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":"SwiNOG 40: When a Routing Control Functions Is Too Fresh « ipSpace.net blog","url":"https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol"},"datePublished":"2026-08-11T08:56:01.781Z","dateModified":"2026-08-11T09:09:33.443Z","description":"A presentation from SwiNOG 40 covers a bug in Arista EOS where defining a new Routing Control Function (RCF) and applying it to BGP routing updates within the...","image":"https://media.daily.dev/image/upload/s--VDukGCjf--/f_auto/v1722860399/public/Placeholder%2002","thumbnailUrl":"https://media.daily.dev/image/upload/s--VDukGCjf--/f_auto/v1722860399/public/Placeholder%2002","isAccessibleForFree":true,"articleSection":"ipSpace.net Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"ipSpace.net Blog","logo":"https://media.daily.dev/image/upload/s--xS7E82MT--/f_auto,q_auto/v1786438303/logos/ipspace?_a=BAMAMicg0","url":"https://daily.dev/sources/ipspace"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"bgp","timeRequired":"PT1M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"ipSpace.net Blog","item":"https://daily.dev/sources/ipspace"},{"@type":"ListItem","position":3,"name":"SwiNOG 40: When a Routing Control Functions Is Too Fresh « ipSpace.net blog"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/swinog-40-when-a-routing-control-functions-is-too-fresh-ipspace-net-blog-ae5cpg2ol#faq","mainEntity":[{"@type":"Question","name":"What happens if you define a new Routing Control Function on Arista EOS and apply it to BGP in the same configuration session?","acceptedAnswer":{"@type":"Answer","text":"Applying a newly defined Routing Control Function (RCF) to BGP routing updates within the same Arista EOS configuration session triggers a bug that causes unexpected behavior. 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