Nvidia (Mellanox) switch: trunk port not passing VLANs

By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30

What this guide covers

Fix trunk port not passing VLANs on a Nvidia (Mellanox) switch.

Step-by-step

1. Confirm trunk both sides match: same VLAN list, same native VLAN.
2. Verify VLAN exists in the VLAN database.
3. Confirm trunk encapsulation type.
4. Check CDP / LLDP neighbours to compare both sides.

CLI / commands

nv show interface
nv show interface swp1
nv show platform inventory

When the issue persists

• Open a Nvidia Enterprise Support case with the tech-support bundle.
• Provide the timeline + recent changes.

Frequently asked questions

Will this work on my specific Cumulus Linux / NVOS / SONiC version?

The procedure reflects current Cumulus Linux / NVOS / SONiC behaviour. Older releases may need minor syntax adjustments, use the CLI help (? or tab-completion) to verify.

Should I open a Nvidia Enterprise Support case immediately?

Open one if you suspect hardware failure or the symptom persists after a maintenance-window reload. Make sure your support entitlement is active first.

Where can I find the Nvidia (Mellanox) official documentation?

https://docs.nvidia.com/networking/. search the product family + feature name.

Is this procedure safe in production?

Test in a lab or maintenance window first. Capture pre-change state so you can roll back.

Related guides

• All Nvidia (Mellanox) fix guides → /nvidia/
• All vendor guides → /vendors/

Related fixes

Related guides worth a look while you sort this one out:

• Nvidia (Mellanox) Switch Port auto-negotiation mismatch (speed / duplex): How to Fix
• Nvidia (Mellanox) Switch Port negotiates 100 Mbps instead of 1 Gbps: How to Fix
• Nvidia (Mellanox) Switch Port PoE device not powering on: How to Fix
• Nvidia (Mellanox) Switch Port stuck disabled by BPDU guard: How to Fix
• Nvidia (Mellanox) Switch Port stuck disabled by link-flap: How to Fix
• Nvidia (Mellanox) Switch Port stuck disabled by loop detection: How to Fix

References

• Nvidia (Mellanox) support portal: https://enterprise-support.nvidia.com/
• Nvidia (Mellanox) knowledge base: https://docs.nvidia.com/networking/
• Nvidia (Mellanox) security advisories: https://www.nvidia.com/en-us/security/
• Open a case: https://enterprise-support.nvidia.com/s/createcase

Reference material, not professional advice. Validate against your specific Cumulus Linux / NVOS / SONiC version and test in a non-production environment before applying.

Why this matters for your day-to-day

A Nvidia device that's misbehaving costs more than the fix itself: lost productivity, missed calls, security risk, even safety risk in some categories. Treating the symptom quickly with a documented procedure is cheaper than letting it persist. The steps above are written to get you back to working in under an hour where possible, and to flag clearly when escalation is the right call.

Before you start

A few things to confirm so the Nvidia device fix goes cleanly:

• Latest firmware downloaded if you're going to update.
• Warranty + support contract status checked, opening sealed parts may void it.
• Backup of current configuration (where applicable) taken.
• Spare parts on hand if you anticipate replacement.
• Adequate workspace, lighting, and time: rushing causes regressions.

Verification checklist

After applying the fix on your Nvidia device, confirm:

• The original symptom is no longer reproducible.
• Related features (status LEDs, app sync, paired accessories) still work.
• The device responds to a soft reboot without the fault returning.
• Any error codes that were on display have cleared.
• Documentation (your service log, the brand companion app) reflects the change.

When to call Nvidia support instead

Escalate if:

• The same symptom returns within 24 hours of a clean fix.
• You see physical damage (burn marks, swollen battery, cracked PCB).
• The device is in warranty and a hardware replacement is the cheaper outcome.
• Repair requires specialised tools you don't own (alignment jigs, calibration software).
• Following the official path keeps the warranty intact, which matters more than the time spent.

More frequently asked questions

How often should I run preventive checks?

Quarterly for most consumer devices; monthly for production / commercial devices. Set a calendar reminder so the device stays healthy between issues.

Why is this happening on a brand-new unit?

Out-of-box defects do occur. If you've owned the device under 30 days and the symptom persists after a factory reset, escalate to the seller for replacement under DOA terms before opening a manufacturer support case.

What if my model isn't exactly the same revision?

Cross-check the model code on the rating plate against the manufacturer support page. Major firmware generations sometimes shift the menu path; the option is usually under a similarly-named section.

Is it safe to apply during business hours?

If the device is in production use, apply during a scheduled maintenance window. Most procedures need 2-15 minutes of downtime. Capture pre-change state so you can roll back if needed.

Does this affect other devices on my network?

Generally no. The procedure is local to this device. Network-side changes (firmware updates that affect TLS, SMB, or routing) are flagged explicitly in the steps.