--- title: Use VRFs for VXLAN-Enabled VLANs « ipSpace.net blog description: Running the same routing protocol (OSPF) in both the VXLAN underlay and on VXLAN-enabled VLAN interfaces causes a routing loop that periodically bricks the... canonical: https://daily.dev/posts/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Use VRFs for VXLAN-Enabled VLANs « ipSpace.net blog | daily.dev og:description: Running the same routing protocol (OSPF) in both the VXLAN underlay and on VXLAN-enabled VLAN interfaces causes a routing loop that periodically bricks the... og:url: https://daily.dev/posts/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd og:image: https://api.daily.dev/og/posts/CdXmaVkFD.png og:image:alt: Use VRFs for VXLAN-Enabled VLANs « 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. # Use VRFs for VXLAN-Enabled VLANs « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 5 min read · 0 upvotes · 0 comments ## Summary Running the same routing protocol (OSPF) in both the VXLAN underlay and on VXLAN-enabled VLAN interfaces causes a routing loop that periodically bricks the network every ~40 seconds. The root cause is that OSPF forms adjacencies over both physical and VLAN interfaces, then prefers the VLAN path to reach the remote loopback, causing VXLAN traffic to try to encapsulate itself over the same VLAN — a classic tunnel-over-tunnel routing problem. Solutions include enabling OSPF only on specific interfaces, making VLAN interfaces passive, or redistributing connected routes. The recommended fix is placing VLAN interfaces in separate VRFs to cleanly separate overlay tenant traffic from underlay transport traffic, preventing tenant routing from polluting the transport network. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does OSPF adjacency keep dropping and re-establishing every 40 seconds on a VXLAN setup with Arista switches? The OSPF dead interval timer (~40 seconds) is the culprit. When OSPF runs on both physical interfaces and VXLAN-enabled VLAN interfaces, it may prefer the VLAN path to reach the remote loopback. This causes VXLAN to try to encapsulate traffic over the same VLAN it depends on, creating a loop. The adjacency forms, routing breaks, the dead interval expires, and the cycle repeats. _Network engineers debugging VXLAN/OSPF interactions find the specific failure patterns on daily.dev._ ### What is the best way to prevent OSPF from forming adjacencies over VXLAN VLAN interfaces in a data center fabric? The recommended approach is to place VLAN interfaces in separate VRFs, which cleanly separates overlay tenant traffic from underlay transport traffic and makes it impossible for tenant routing to pollute the transport network. Alternatives include enabling OSPF only on physical interfaces with connected route redistribution, or making VLAN interfaces passive in OSPF to prevent adjacency formation over them. _Teams designing VXLAN fabrics and weighing these trade-offs track architecture decisions like this on daily.dev._ ## Similar posts on daily.dev - [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/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd) ```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":"Use VRFs for VXLAN-Enabled VLANs « ipSpace.net blog","url":"https://daily.dev/posts/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd"},"datePublished":"2026-08-11T08:52:06.144Z","dateModified":"2026-08-11T09:02:33.633Z","description":"Running the same routing protocol (OSPF) in both the VXLAN underlay and on VXLAN-enabled VLAN interfaces causes a routing loop that periodically bricks the...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/1efd83358be121a0955154e8b5e46c42?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/1efd83358be121a0955154e8b5e46c42?_a=AQAEuop","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/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT5M"} {"@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":"Use VRFs for VXLAN-Enabled VLANs « ipSpace.net blog"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/use-vrfs-for-vxlan-enabled-vlans-ipspace-net-blog-cdxmavkfd#faq","mainEntity":[{"@type":"Question","name":"Why does OSPF adjacency keep dropping and re-establishing every 40 seconds on a VXLAN setup with Arista switches?","acceptedAnswer":{"@type":"Answer","text":"The OSPF dead interval timer (~40 seconds) is the culprit. 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