NVIDIA/Mellanox MSN4700-WS2FC Mellanox Spectrum-3 Based 400GbE 1U Open Ethernet Switch with Cumulus Linux, 32 QSFP-DD Ports, 2 Power Supplies (AC),x86 CPU, Standard Depth, P2C Airflow, Rail Kit

The choice depends on reach and future expansion plans. DAC is typically the most practical option for very short in-rack links. AOC is suitable for short point-to-point optical connections. DR4 is a strong option for parallel single-mode fiber deployments, especially when a future 4×100GbE breakout is required. FR4 or LR4 is better suited to longer duplex-fiber links, but these WDM optics cannot be split into separate lower-speed connections.

Yes. All 32 QSFP-DD ports on the SN4700 can operate in a 4×100GbE breakout design, providing up to 128×100GbE connections without disabling adjacent ports. This allows customers to build a 400GbE core or spine layer first, then migrate leaf, GPU, or storage uplinks to 200GbE or 400GbE as the environment evolves.

In addition to checking the media type, FEC, and far-end speed, verify the Cumulus Linux lane configuration. In certain Cumulus Linux releases, a four-way breakout between an SN4700 and a Spectrum-based peer can fail with the default lanes-per-port setting. Follow the release-specific NVIDIA guidance for breakout parameters and validate the end-to-end link before large-scale deployment.

Not always. When the SN4700 acts only as an underlay router, EVPN route-exchange device, or route reflector—and does not terminate tenant traffic as a VTEP—it typically does not require local VXLAN tunnel interfaces. VXLAN configuration is needed when the switch must terminate VNIs, map local VLANs to VNIs, or provide gateway functions.

It should not be assumed. Dual AC PSUs provide power redundancy, but NVIDIA release notes identify potential transient frame loss on the SN4700 during PSU insertion or removal in certain Cumulus Linux releases. Treat PSU replacement as a controlled maintenance activity: confirm that the remaining power feed has sufficient capacity, ensure workloads have resilient paths, and review the release notes for the installed software version.