--- title: Mellanox NICs with VLAN-Aware Bridges on Linux | daily.dev description: Enabling VLAN-aware bridges in Proxmox on Mellanox ConnectX-4 NICs can cause all network traffic to stop due to the mlx5 driver's inability to handle large... canonical: https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Mellanox NICs with VLAN-Aware Bridges on Linux | daily.dev og:description: Enabling VLAN-aware bridges in Proxmox on Mellanox ConnectX-4 NICs can cause all network traffic to stop due to the mlx5 driver's inability to handle large... og:url: https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am og:image: https://api.daily.dev/og/posts/V8S24w8aM.png og:image:alt: Mellanox NICs with VLAN-Aware Bridges on Linux 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. # Mellanox NICs with VLAN-Aware Bridges on Linux **[apalrd's adventures](https://daily.dev/sources/apalrd)** · 3 min read · 0 upvotes · 0 comments ## Summary Enabling VLAN-aware bridges in Proxmox on Mellanox ConnectX-4 NICs can cause all network traffic to stop due to the mlx5 driver's inability to handle large VLAN lists. The fix involves two steps: enabling promiscuous mode on the NIC interface (`ip link set dev promisc on`) and, if VLAN offload errors persist, disabling the hardware VLAN filter via `ethtool -K rx-vlan-filter off`. The root cause is that the mlx5 driver limits hardware VLAN offloading to 512 entries; without promiscuous mode (which bonds enable automatically), the driver fails entirely. Both fixes can be persisted in `/etc/network/interfaces`. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does enabling a VLAN-aware bridge in Proxmox stop all traffic on my Mellanox NIC? The mlx5 driver for Mellanox NICs limits hardware VLAN offloading to 512 entries. When a VLAN-aware bridge tags a large range of VIDs (e.g., 2–4094), the driver logs 'vlans list size > max vport list size' and fails to pass traffic entirely. Enabling promiscuous mode on the interface (`ip link set dev promisc on`) resolves the traffic stoppage; disabling rx-vlan-filter via ethtool eliminates the remaining errors. _Engineers troubleshooting Mellanox and Proxmox networking edge cases share fixes like this on daily.dev._ ### How do I disable hardware VLAN filtering on a Mellanox NIC in Linux to fix vlan offload errors? Run `ethtool -K rx-vlan-filter off` to disable hardware VLAN filtering on a Mellanox NIC. This prevents the mlx5 driver from attempting to offload all VLANs to hardware, eliminating 'vlans list size > 512' errors in dmesg. To make it persistent, add a `post-up ethtool -K rx-vlan-filter off` line in `/etc/network/interfaces`. _Linux networking fixes for specific NIC quirks like this surface regularly among homelab and sysadmin communities on daily.dev._ ## Similar posts on daily.dev - [Stop putting off VLANs in your homelab — Proxmox SDN makes them almost too easy](https://daily.dev/posts/stop-putting-off-vlans-in-your-homelab-proxmox-sdn-makes-them-almost-too-easy-p4xrm9vtr) · XDA Developers · 0 upvotes · 0 comments - [Running VyOS on a Mellanox SN2010 Switch](https://daily.dev/posts/running-vyos-on-a-mellanox-sn2010-switch-xm7gdppnh) · scottstuff.net · 0 upvotes · 0 comments - [Using The New Bridges of FreeBSD 15](https://daily.dev/posts/using-the-new-bridges-of-freebsd-15-culpd1o2p) · Hacker News · 0 upvotes · 0 comments - [Introduction to Linux interfaces for virtual networking](https://daily.dev/posts/introduction-to-linux-interfaces-for-virtual-networking-cct7can4a) · Red Hat Developer · 0 upvotes · 0 comments --- Tags: [#proxmox](https://daily.dev/tags/proxmox) [View this post on daily.dev](https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am) ```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":"Mellanox NICs with VLAN-Aware Bridges on Linux","url":"https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am"},"datePublished":"2026-08-11T08:56:31.733Z","dateModified":"2026-08-11T09:33:50.658Z","description":"Enabling VLAN-aware bridges in Proxmox on Mellanox ConnectX-4 NICs can cause all network traffic to stop due to the mlx5 driver's inability to handle large...","image":"https://media.daily.dev/image/upload/s--0_ODbtD2--/f_auto/v1722860399/public/Placeholder%2008","thumbnailUrl":"https://media.daily.dev/image/upload/s--0_ODbtD2--/f_auto/v1722860399/public/Placeholder%2008","isAccessibleForFree":true,"articleSection":"apalrd's adventures","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":"apalrd's adventures","logo":"https://media.daily.dev/image/upload/s--4zkx8dRj--/f_auto,q_auto/v1786438309/logos/apalrd?_a=BAMAMicg0","url":"https://daily.dev/sources/apalrd"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"proxmox","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"apalrd's adventures","item":"https://daily.dev/sources/apalrd"},{"@type":"ListItem","position":3,"name":"Mellanox NICs with VLAN-Aware Bridges on Linux"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/mellanox-nics-with-vlan-aware-bridges-on-linux-v8s24w8am#faq","mainEntity":[{"@type":"Question","name":"Why does enabling a VLAN-aware bridge in Proxmox stop all traffic on my Mellanox NIC?","acceptedAnswer":{"@type":"Answer","text":"The mlx5 driver for Mellanox NICs limits hardware VLAN offloading to 512 entries. When a VLAN-aware bridge tags a large range of VIDs (e.g., 2–4094), the driver logs 'vlans list size > max vport list size' and fails to pass traffic entirely. Enabling promiscuous mode on the interface (`ip link set dev promisc on`) resolves the traffic stoppage; disabling rx-vlan-filter via ethtool eliminates the remaining errors. Engineers troubleshooting Mellanox and Proxmox networking edge cases share fixes like this on daily.dev."}},{"@type":"Question","name":"How do I disable hardware VLAN filtering on a Mellanox NIC in Linux to fix vlan offload errors?","acceptedAnswer":{"@type":"Answer","text":"Run `ethtool -K rx-vlan-filter off` to disable hardware VLAN filtering on a Mellanox NIC. This prevents the mlx5 driver from attempting to offload all VLANs to hardware, eliminating 'vlans list size > 512' errors in dmesg. To make it persistent, add a `post-up ethtool -K rx-vlan-filter off` line in `/etc/network/interfaces`. Linux networking fixes for specific NIC quirks like this surface regularly among homelab and sysadmin communities on daily.dev."}}]} ```