Nvidia (Mellanox): 40G QSFP+ breakout to 4x10G SFP+

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

Quick answer

Use a QSFP+ to 4x SFP+ MPO-to-LC breakout. QSFP+ side into the 40G port, 4 SFP+ into 10G ports.

How to pick the right cable / optic

1. Identify the link speed (1G / 10G / 25G / 40G / 100G).
2. Identify the distance (in-rack, in-room, cross-building, long-haul).
3. Identify the connector type on each end (RJ-45, LC, MPO, QSFP).
4. Check the Nvidia (Mellanox) supported transceiver matrix for your platform.
5. Use OEM-branded for production; third-party for lab or non-critical.

CLI to verify installed optics

nv show interface
nv show interface swp1

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): SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28
• Best Nvidia (Mellanox) switch for branch office
• Best Nvidia (Mellanox) switch for enterprise data centre
• Best Nvidia (Mellanox) switch for retail store
• Best Nvidia (Mellanox) switch for SD-WAN deployment
• Best Nvidia (Mellanox) switch for small office

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.

How to confirm it's actually fixed

On a Nvidia device, the test is rarely "reboot and see". Use this list:

• Active reproduction: trigger the original failure path on purpose.
• Indirect reproduction: do an activity that would expose the same subsystem.
• Status indicator review: every LED / display / app status should be green.
• 24-hour soak: leave the device under normal load overnight; check the next morning.
• Telemetry check: review the device or app's diagnostic log for new error entries.

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

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.

Can I roll this back if something breaks?

Yes for software-level changes (firmware rollback, config rollback). Hardware changes are usually one-way. Always back up settings before starting.

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.

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.

Will the procedure work on the international variant?

Some features and firmware paths are region-locked. Check the model spec sheet to confirm your variant supports the menu option referenced. If you're outside the US/EU, look for the regional support portal.