NVIDIA Spectrum-X SN5600
The SN5600 is a 64-port 800GbE Spectrum-4 switch and the leaf/spine building block of Spectrum-X, NVIDIA's Ethernet alternative to InfiniBand for AI training and inference fabrics. On its own it is a 51.2 Tb/s cut-through Ethernet switch. Paired with BlueField-3 SuperNICs on the host side, it becomes the full Spectrum-X stack: lossless RoCE, per-packet adaptive routing and telemetry-based congestion control tuned for GPU collective traffic. Buy it as a commodity switch or as one half of a matched fabric; the two behave very differently.
- InfiniBand vs. Spectrum-X is a fabric decision, not a switch spec sheet decision: InfiniBand stays more deterministic for tight GPU collective synchronization; Spectrum-X trades a little of that determinism for Ethernet-standard tooling, ops staffing, and multi-vendor optics.
- Adaptive routing and RoCE congestion control are a matched-pair feature: they only fully engage when BlueField-3 sits on the other end of the link. Mixing an SN5600 with third-party or older ConnectX NICs falls back to plain ECMP RoCEv2, which is a meaningfully different fabric.
- One 51.2 Tb/s ASIC replacing what used to take two Spectrum-3 switches cuts rack count and fiber runs for a given port count; that consolidation is the practical reason to move off Spectrum-3, independent of the AI-specific features.
- 940 W typical per switch sounds small next to a GPU node, but a spine/leaf Spectrum-X fabric runs dozens of these; budget PDU and cooling headroom for the switch tier separately from the compute tier, not as a rounding error on it.
- "Call for availability" pricing from every reseller checked means real lead time and volume pricing only shows up once you are in a live quote; do not plan a build timeline off a website price alone.
Is Spectrum-X the same thing as InfiniBand?
No. Spectrum-X is an Ethernet fabric (Spectrum-4 switches like the SN5600 plus BlueField-3 SuperNICs) engineered to behave more like InfiniBand: lossless transport, per-packet adaptive routing, and telemetry-driven congestion control. It is NVIDIA's Ethernet answer to InfiniBand for AI clusters, not a rebrand of InfiniBand itself.
Does the SN5600 need BlueField-3 to work?
No, it functions as a standard 51.2 Tb/s Ethernet switch with any RoCE-capable NIC. But the Spectrum-X-specific behavior, adaptive routing and telemetry-based congestion control, requires BlueField-3 SuperNICs on the connected hosts to fully engage.
How much does an SN5600 cost?
Reported street pricing runs roughly $65,000 to $87,000 per unit for a new switch, before optics, cables, or NICs, based on Hardware Nation and Avendor listings. Get a live quote for volume or allocation pricing.
What cabling does the SN5600 use?
64 OSFP ports supporting 10 through 800 GbE via passive DAC, active AEC, or optical transceivers, plus one SFP28 port for out-of-band management (1/10/25 GbE).