Nvidia (Mellanox) Switch Port stuck disabled by loop detection: How to Fix
By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30
| Vendor | Nvidia (Mellanox) |
|---|---|
| Operating system | Cumulus Linux / NVOS / SONiC |
| Category | Port Recovery |
| Skill level | Intermediate to advanced |
| DIY-able? | Yes with CLI access; some scenarios need Nvidia Enterprise Support + RMA. |
What this guide covers
Resolve a Nvidia (Mellanox) switch port loop detection.
Cause + fix
Loop detected on the port. Fix the physical loop, then bounce the port.
CLI / commands
nv show interface
nv show interface swp1
# Apply the fix above, then bounce the port:
nv config (NVUE)
# (interface shutdown / no shutdown. vendor-specific)
nv config save
Avoid recurrence
- Identify and remove the source of the violation (BPDU, MAC, storm).
- Tune the protection threshold if it's too aggressive for normal traffic.
- Add monitoring for repeat events.
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
Related fixes
Related guides worth a look while you sort this one out:
- 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 PoE budget exceeded: How to Fix
- Nvidia (Mellanox) Switch Port stuck disabled by port security violation: How to Fix
- Nvidia (Mellanox) Switch Port stuck disabled by storm-control: How to Fix
- Nvidia (Mellanox) Switch Port stuck disabled by UDLD: 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.
Common patterns we see
When this symptom shows up on a Nvidia device, three patterns repeat:
1. Recent firmware update changed behavior, the symptom started within a week of an OTA push. Rollback or wait for the hotfix. 2. Environmental trigger. temperature, humidity, line voltage, network changes. Look at what changed in the environment. 3. Cumulative wear, components like batteries, gaskets, fans degrade over time. Replace the consumable rather than chasing a software fix.
Knowing which pattern applies saves time on the wrong fix.
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.
Quick verification
Before you walk away from a Nvidia device fix, run through:
1. Reproduce the original trigger. does the issue reappear? 2. Check the device's status / health screen for any new alerts. 3. Confirm paired devices (app, hub, controller) reconnected. 4. Save / commit any configuration changes per the device's normal workflow. 5. Note the change in your maintenance log with date + firmware version.
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 long does this fix usually take?
Most users complete the steps in 20-45 minutes the first time, and 5-10 minutes on subsequent runs once the menu paths are familiar.
Will this void my warranty?
Applying official firmware updates and following the user manual will not affect warranty. Opening sealed components, jumping safety circuits, or using third-party parts can void warranty in most jurisdictions.
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.
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.