Cumulus Linux, Onyx, and SONiC are not interchangeable software images. The correct choice depends on the exact switch OPN, Spectrum generation, NOS version, optics, automation model, licensing position, and support contract.
- Why the complete OPN is required before choosing a NOS
- When operational continuity is more important than migration
- Automation, Linux operations, EVPN, VXLAN, and support considerations
- Team capabilities, SAI integration, and support responsibility
- Migration planning, PSID checks, configuration conversion, and rollback
- Software entitlement, support status, and information to prepare
- A practical NOS selection rule for NVIDIA Spectrum switches
The Three NOS Options Are Not Interchangeable
NVIDIA Spectrum platforms can be used with Cumulus Linux, SONiC, and Onyx, but the three systems provide different operational models. The choice affects interface configuration, routing, automation, software updates, troubleshooting, and support.
| NOS | Best Fit | Main Strength | Main Risk |
|---|---|---|---|
| Cumulus Linux | New production deployments and automated data center networks | Linux-based workflow with NVUE and automation options | License, version, and migration planning |
| Onyx | Stable existing installations | Lowest disruption when the current network is already validated | Long-term maintenance and migration pressure |
| SONiC | Cloud-scale and highly customized network environments | Open architecture based on SAI and modular components | Higher integration, testing, and support responsibility |
NVIDIA describes Cumulus Linux, SONiC, and Onyx as software options associated with Spectrum-based switching platforms. This does not mean that every NOS version is supported on every Spectrum switch. The exact hardware, image, release, and support model must be confirmed before deployment.
Send the switch OPN, current NOS, target software, and optics list for a configuration review.
Start with the Exact Spectrum Switch SKU
A family name such as SN2000, Spectrum, or SN5000 is not enough to confirm NOS compatibility. The exact OPN may affect supported images, port breakout behavior, optics, PSID restrictions, hardware support, and software licensing.
For example, the MSN2010-CB2RC has a different port role from the MSN2100-CB2F. A high-density platform such as the SN2700 also requires separate checks for port density, airflow, optics, and fabric design.
- Exact switch OPN
- Spectrum ASIC generation
- Current NOS and software version
- Current PSID
- Installed optics, DACs, and AOCs
- Required port speeds and breakout modes
- EVPN, VXLAN, MLAG, or storage-fabric requirements
- Required automation and monitoring tools
- Current support contract
- Target maintenance and rollback plan
When Should You Stay on Onyx?
Staying on Onyx can be the lowest-risk choice when the existing network is stable and the operations team already knows how to maintain it.
- The current configuration is working reliably.
- The team depends on existing Onyx CLI or Web UI procedures.
- Monitoring, backup, and automation tools are already built around Onyx.
- The network does not require a feature available only in another NOS.
- The current hardware and software combination remains supported.
- There is no suitable maintenance window for a disruptive migration.
Keeping Onyx for an existing validated deployment is not the same as recommending it for every new installation. Before continuing with Onyx, verify the current version, hardware support, available software downloads, and support contract.
Forum discussions may indicate that users are considering alternatives, but they should not be used as an official EOL announcement. Any lifecycle statement should be supported by a current NVIDIA notice or contract-specific information.
When Does Cumulus Linux Make More Sense?
Cumulus Linux is often the first option to evaluate when a new Spectrum deployment requires a Linux-based network operating model and a documented NVIDIA software path.
- NVUE-based configuration
- Linux-based troubleshooting
- Ansible or other automation workflows
- BGP EVPN and VXLAN
- MLAG and Layer 3 fabric designs
- Network telemetry and operational monitoring
- A defined process for software updates and support
Cumulus Linux also changes the operating model. Engineers moving from a traditional switch CLI should plan for new configuration workflows, Linux file and service management, NVUE commands, different backup procedures, and different upgrade behavior.
Cumulus Linux is not simply Onyx with a different command syntax. The network design, configuration model, automation process, and operational documentation should be reviewed together.
When Is SONiC the Right Choice?
SONiC can be appropriate when an organization wants an open, modular NOS architecture and has the engineering capability to manage more of the integration process.
SONiC is more suitable for teams that already have strong Linux administration, SAI, automation, CI/CD, configuration testing, and in-house monitoring capabilities.
- Strong Linux and network software skills
- Experience with SAI and switching ASIC abstraction
- Automated configuration and testing
- A defined source for software support
- A lab environment for the exact switch platform
- Clear responsibility for security updates and troubleshooting
SONiC should not be selected only because it is open source. The team must verify the target image, supported features, optics, breakout ports, release process, security updates, and technical support model.
For a small enterprise network without SONiC operating experience, the integration and troubleshooting effort may outweigh the expected licensing benefit.
Onyx to Cumulus Migration Risks
An Onyx-to-Cumulus project is a software replacement and validation project. It should not be planned as a simple configuration-file import.
- Record the exact hardware OPN, PSID, serial number, and current software version.
- Back up the running configuration and operational documentation.
- Record all optics, DACs, AOCs, breakout cables, and port mappings.
- Confirm that the target Cumulus version supports the hardware.
- Confirm Cumulus licensing and support entitlement.
- Review Onyx-specific commands and identify configuration changes.
- Schedule a maintenance window and define a rollback path.
- Uninstall the existing Onyx image through the supported ONIE process.
- Install the target Cumulus image.
- Restore or rebuild the configuration.
- Validate interfaces, optics, VLANs, BGP, MLAG, EVPN, VXLAN, and management access.
- Monitor the switch after migration.
NVIDIA states that Onyx must be uninstalled before Cumulus Linux is installed. The official migration guidance also warns that some older Onyx versions may require PSID changes to remove image and optics restrictions. An incorrect PSID change can make the switch inoperable, so this step should not be treated as a routine command-line operation.
Configuration conversion tools may reduce manual work, but they do not eliminate the need to review interfaces, routing, MLAG, EVPN, optics, management access, and monitoring independently.
Licensing, Support, and Procurement Checklist
Image Installation Is Not the Same as Software Support
Installing a Cumulus Linux image does not by itself prove that the software is licensed or supported. For Cumulus Linux 4.4 and later, a separate license key is no longer required to enable the switchd service, but the appropriate software license and support entitlement are still required.
| Check | Question to Confirm |
|---|---|
| Image installation | Can the selected image be installed on this hardware? |
| Software entitlement | Does the customer have the right to use the NOS? |
| Version support | Is the selected release still supported? |
| Hardware support | Is the switch covered by the applicable support product? |
| Optics support | Are the installed modules supported on the selected NOS? |
| Rollback | Can the team safely return to the previous NOS? |
Information to Prepare Before a NOS Consultation
- Exact switch model and OPN
- Current NOS and version
- Target NOS and version
- Current PSID
- Hardware and ASIC generation
- Current network topology
- MLAG, EVPN, VXLAN, BGP, or storage requirements
- Optics, DACs, AOCs, and breakout cables
- Automation and monitoring tools
- Required support level
- Maintenance window and rollback requirements
A complete request makes it easier to separate a software-selection question from a hardware-compatibility or licensing question.
Final Takeaway
Cumulus Linux, Onyx, and SONiC solve different operational problems.
- Choose Cumulus Linux for a new Spectrum deployment that needs Linux-based automation and a documented NVIDIA software path.
- Keep Onyx when an existing environment is stable, supported, and costly to migrate.
- Choose SONiC when the organization has the engineering capability to manage SAI, automation, image validation, and software support.
The safest selection process starts with the exact switch OPN and current NOS version. Confirm hardware compatibility, PSID, optics, licensing, support, migration tooling, and rollback requirements before changing the software image.