Dell PowerSwitch SN5400 400GbE Switch

The Dell PowerSwitch SN5400 is a 2U smart-leaf, spine and super-spine switch with 64 QSFP-DD ports of 400GbE plus two 25GbE SFP28 ports, built on the NVIDIA Spectrum-4 ASIC, delivering 25.6 Tbps of bidirectional switching capacity, 33.3 Bpps of forwarding and a 160MB fully shared packet buffer.

It is the 400GbE member of an otherwise-800GbE family, and it is the one model NVIDIA excludes from the Spectrum-X platform. Both facts are the reason to read this page rather than treating the SN5400 as a cheaper SN5610.

The Spectrum-X exclusion, stated plainly

NVIDIA's sentence about the SN5000 series contains a parenthesis that decides deployments: the Spectrum-X platform "integrates Spectrum 5000 series Ethernet switches (excluding SN5400) with NVIDIA SuperNICs, standing out as the world's first Ethernet fabric built specifically for AI."

The SN5400 runs the same Spectrum-4 silicon as its siblings, carries the same 160MB monolithic buffer, the same 512,000 shared forwarding entries and the same 33.3 Bpps packet rate. What it does not carry is membership of the switch-plus-SuperNIC system that NVIDIA credits with a 1.6x generative-AI performance improvement over conventional Ethernet fabrics, along with performance isolation across thousands of simultaneous AI jobs.

What follows from that is a clean decision rule. If the fabric design depends on Spectrum-X behaviour - if it assumes the end-to-end codesign with BlueField and ConnectX SuperNICs, or the job-level isolation - then the switch must be an SN5610 or SN5600D and the SN5400 will not substitute. If the design is a conventional high-performance Ethernet fabric, or a 400G data centre build that is not a GPU pod, the exclusion costs nothing and the SN5400 is the right port-cost-per-gigabit. Dell positions it exactly there: "ideal for 400 G data center fabrics".

QSFP-DD, not OSFP - and this is the family split

The SN5400's connector is QSFP-DD. The SN5610 and SN5600D on the same datasheet use OSFP. The cages are not interchangeable, and because all three models share a page it is genuinely easy to order the wrong optics.

The mechanism behind the difference is the lane rate. The SN5400's QSFP-DD cage runs 8 lanes of 50G PAM4 - 400Gb/s per port, 25.6 Tb/s across 64 ports. The 800G models' OSFP cages run 8 lanes of 100G PAM4. Same lane count, double the rate, different form factor.

The other QSFP-DD model in the Dell AI range is the SN4700, so a site standardising on QSFP-DD optics can pair the two without splitting its spares inventory.

The port map

Port speeds span 1 to 400 Gb/s. Reachable densities:

• 64 x 400GbE native QSFP-DD
• 128 x 200GbE, and the same figure at 40GbE
• 256 x 100GbE, and the same at 50GbE
• 256 + 2 x 25GbE and 10GbE - the +2 being the SFP28 ports

Two hundred and fifty-six ports of 100GbE from two rack units is the figure that justifies the chassis. NVIDIA positions the SN5000 series as suitable for replacing modular chassis switches, and this is the model where that argument is most compelling because the port economics are better than on the 800G members.

One specification looks like a transcription error and is not: the packet rate is 33.3 Bpps, identical to the SN5610 and SN5600D, even though the switching capacity is half theirs. Bandwidth halves with the lane rate; the packet-processing pipeline does not change. On small-packet workloads the SN5400 forwards at the same rate as its 800G siblings.

Spectrum-4 for AI and cloud traffic

The 160MB packet buffer is monolithic and fully shared across all ports, supporting cut-through traffic from every port at once. That architecture is what makes performance predictable under incast, which on any synchronised workload - AI training above all - is the normal operating pattern rather than an occasional event.

Around it: RoCE for RDMA workloads, single-pass VXLAN routing and bridging, cloud-scale network address translation, a programmable pipeline with a deep packet parser and editor processing payloads to the first 512 bytes, 512,000 forwarding entries dynamically shared across MAC, ARP, IPv4 routes, ACLs, ECMP and VXLAN tunnels, and 256-way ECMP. High availability comes from EVPN multi-homing, multi-chassis LAG for active/active Layer 2 multipathing, and hardware-assisted in-service software upgrades.

Visibility is the full Spectrum stack - What Just Happened event-triggered telemetry, hardware-accelerated queue-depth histograms powered by NetQ at sub-microsecond granularity, inband network telemetry, streaming telemetry, 512,000 on-chip flow counters. Security is a built-in hardware root of trust authenticating BIOS through network operating system; anything not signed by NVIDIA is blocked from running.

Power, cooling and physical planning

Two hot-swappable power supplies in 1+1 redundancy at 50-60Hz, 200-240V AC. Note the 200V floor - there is no low-line option. Cooling is four hot-swappable fans in N+1 redundancy.

Airflow is the one place the SN5400 is more flexible than its siblings: the datasheet lists "reverse, forward" for this model and reverse only for the SN5610 and SN5600D. If the rack layout requires front-to-back airflow, the SN5400 is the only SN5000 that can provide it, and that is occasionally the deciding factor on its own.

The chassis is 3.39 in high, 17.20 in wide and 31.00 in deep - full-depth cabinet, plus rear clearance for cabling. Operating envelope 0 to 35 C, non-operating -40 to 70 C, relative humidity 5-85%, altitude to 3,050 m.

The SN5000 family datasheet publishes no weight, no power draw and no latency figure for any of its three models. Freight, circuit sizing and latency budgets need a physical unit or a Dell quote; nothing is estimated here from the form factor.

Software

NVIDIA Cumulus Linux or Enterprise SONiC Distribution by Dell Technologies, on an ONIE platform that will install alternatives. NVIDIA Air builds a digital twin of the switch and every cable so policy, automation, monitoring, interoperability and upgrade procedures can be validated before the hardware arrives. On a secondary-market unit the installed image tells you nothing about licensing - confirm the NOS before purchase.

Where it sits in the range

The SN5610 and SN5600D are the 800GbE members of the family, the latter DC-fed for bus-bar racks. The SN4700 is the previous Spectrum-3 generation at 32 x 400GbE in 1RU - half the ports of the SN5400 in half the height, and the closer comparison if the requirement is a spine rather than a leaf. On the Dell-branded side the Z9664F-ON is a 64-port 400GbE PowerSwitch and the Z9432F-ON the 32-port 1RU option. If the fabric is InfiniBand, the equivalent tier is the Quantum-2 QM9700; the Dell AI fabric switch guide compares the paths. The out-of-band network is Ethernet either way - that is the SN2201. The full set is listed on our AI and high-speed switch lineup.

Every unit is professionally reconditioned, fully tested and shipped with warranty. This model is quote-only. Tell us the port map, optics plan, airflow direction and quantity and a specialist will come back to you on sourcing and availability.

Specifications