--- title: Stub Networks in Virtual Labs « ipSpace.net blog | daily.dev description: When building virtual network labs, stub segments (connected to a single router/switch) are needed to inject IP subnets into routing protocols without spinning... canonical: https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Stub Networks in Virtual Labs « ipSpace.net blog | daily.dev og:description: When building virtual network labs, stub segments (connected to a single router/switch) are needed to inject IP subnets into routing protocols without spinning... og:url: https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in og:image: https://api.daily.dev/og/posts/nI9sQS7iN.png og:image:alt: Stub Networks in Virtual Labs « 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. # Stub Networks in Virtual Labs « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 4 min read · 0 upvotes · 0 comments ## Summary When building virtual network labs, stub segments (connected to a single router/switch) are needed to inject IP subnets into routing protocols without spinning up full hosts. For KVM/QEMU VMs, this is trivial using UDP tunnels with a bogus remote IP. For containers, containerlab's dummy interfaces seemed ideal but have quirks: the UNKNOWN interface state and zero min/max MTU values cause VyOS to fail unless stub interfaces are renamed from 'eth' to 'dum' prefixes. Arista cEOS won't run OSPF on dummy interfaces unless the network type is set to point-to-point. Netlab release 1.9.4-post1 addresses the Arista cEOS issue by automatically changing the OSPF network type on stub interfaces. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why won't Arista cEOS run OSPF on a containerlab dummy interface? Arista cEOS will not participate in OSPF on a dummy interface unless the OSPF network type is explicitly set to point-to-point. The interface appears in the running config with an IP and OSPF area configured, but is absent from 'show ip ospf int brief' until you apply 'ip ospf network point-to-point'. Netlab release 1.9.4-post1 applies this workaround automatically for stub interfaces. _Engineers running Arista cEOS in virtual labs track fixes like this on daily.dev._ ### Why does VyOS fail on containerlab dummy interfaces with eth names? VyOS checks the minimum and maximum MTU of Ethernet interfaces, and Linux dummy interfaces report both as zero, causing VyOS to fail. The workaround is to rename stub dummy interfaces from the 'eth' prefix to 'dum' (e.g., dum0), since VyOS performs the MTU check on 'eth' interfaces but not on 'dum' interfaces. _Network engineers working around containerlab quirks find relevant workarounds on daily.dev._ ## Similar posts on daily.dev - [Networking Aspects of Running VMs in Containers « ipSpace.net blog](https://daily.dev/posts/networking-aspects-of-running-vms-in-containers-ipspace-net-blog-gttjndloc) · ipSpace.net Blog · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in) ```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":"Stub Networks in Virtual Labs « ipSpace.net blog","url":"https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in"},"datePublished":"2026-08-11T08:52:04.366Z","dateModified":"2026-08-11T08:55:18.057Z","description":"When building virtual network labs, stub segments (connected to a single router/switch) are needed to inject IP subnets into routing protocols without spinning...","image":"https://media.daily.dev/image/upload/s--CxzD6vbw--/f_auto/v1722860399/public/Placeholder%2005","thumbnailUrl":"https://media.daily.dev/image/upload/s--CxzD6vbw--/f_auto/v1722860399/public/Placeholder%2005","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/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT4M"} {"@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":"Stub Networks in Virtual Labs « ipSpace.net blog"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/stub-networks-in-virtual-labs-ipspace-net-blog-ni9sqs7in#faq","mainEntity":[{"@type":"Question","name":"Why won't Arista cEOS run OSPF on a containerlab dummy interface?","acceptedAnswer":{"@type":"Answer","text":"Arista cEOS will not participate in OSPF on a dummy interface unless the OSPF network type is explicitly set to point-to-point. 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