NVIDIA Spectrum-2 SN3420
The NVIDIA Spectrum-2 SN3420 is an enterprise 1U datacenter top-of-rack leaf switch delivering 48 ports of 10G/25G SFP28 and 12 ports of 40G/100G QSFP28. Powered by the Spectrum-2 ASIC delivering 4.8 Tbps of switching throughput, the SN3420 provides an ideal 2:1 oversubscription ratio for high-density compute racks. With deep in-band network telemetry (WJH - What Just Happened), line-rate EVPN-VXLAN, and RoCE v2 acceleration, the SN3420 commands high demand on secondary broker desks.
Specifications
| Brand | NVIDIA |
|---|---|
| Family | Spectrum |
| Form factor | 1U fixed switch |
| Released | Jun 2019 |
| Ports | 48x 10G/25G SFP28 and 12x 40G/100G QSFP28 uplinks |
| Switching capacity | 4.8 Tbps / 3.58 Bpps forwarding rate |
| Silicon | NVIDIA Spectrum-2 programmable 16nm network processing ASIC |
| Telemetry | NVIDIA WJH (What Just Happened) hardware-based packet telemetry |
| Power supplies | Dual redundant hot-swappable AC or DC power modules |
Generations
- Previous generation: NVIDIA Spectrum SN2410
- Next generation: NVIDIA Spectrum-3 SN4410
Works together
How the NVIDIA Spectrum-2 SN3420 connects to servers, storage and the network: 3 ways, with the parts and products on each path.
iSCSI and NVMe/TCP over Ethernet
Keep the speed the same at all three points: a 25GbE server, a 25GbE switch port and a 25GbE array port. Mixed speeds work but the slowest link sets the pace.
Servers
Dell PowerEdge R6515 1U rack
Dell PowerEdge R7515 2U rack
HPE Edgeline EL8000 5U ruggedized edge system
HPE ProLiant DL160 Gen10 1U rack
HPE ProLiant DL180 Gen10 2U rack
Lenovo ThinkSystem SE350 1U rack
Adapters for the server
MBF2H516C-CESCOT NVIDIA BlueField-2 DPU Dual-Port 25GbE SFP28 16GB Arm Crypto PCIe 4.0 x8 Data Processing Unit
MCX512A-ACAT NVIDIA ConnectX-5 EN Dual-Port 25GbE SFP28 PCIe 3.0 x8 Low-Profile Ethernet Network Adapter
MCX556A-ECAT NVIDIA ConnectX-5 VPI Dual-Port 100Gb/s EDR InfiniBand and 100GbE QSFP28 PCIe 3.0 x16 Adapter
MCX623105AN-VDAT NVIDIA ConnectX-6 Dx EN Dual-Port 25GbE SFP56 PCIe 4.0 x16 Ethernet Network Adapter
Storage
Dell Unity XT 380F 2U rack
Dell Unity XT 380XT 2U rack
Dell Unity XT 480F 2U rack
Dell Unity XT 480XT 2U rack
Dell Unity XT 680F 2U rack
Dell Unity XT 680XT 2U rack
Optics
MMA1T00-HS NVIDIA HDR 200Gb/s QSFP56 MPO Optical Transceiver
MMA4Z00-NS NVIDIA NDR 400Gb/s OSFP Optical Transceiver
QSFP-100G-SR4 Arista 100GBASE-SR4 QSFP28 Optical Transceiver
File storage (NFS and SMB)
Front-end ports face the clients; back-end ports (on scale-out systems) connect the nodes to each other and need their own switch pair.
Servers
- Dell PowerEdge R6515 1U rack
- Dell PowerEdge R7515 2U rack
- HPE Edgeline EL8000 5U ruggedized edge system
- HPE ProLiant DL160 Gen10 1U rack
- HPE ProLiant DL180 Gen10 2U rack
- Lenovo ThinkSystem SE350 1U rack
Adapters for the server
- MBF2H516C-CESCOT NVIDIA BlueField-2 DPU Dual-Port 25GbE SFP28 16GB Arm Crypto PCIe 4.0 x8 Data Processing Unit
- MCX512A-ACAT NVIDIA ConnectX-5 EN Dual-Port 25GbE SFP28 PCIe 3.0 x8 Low-Profile Ethernet Network Adapter
- MCX623105AN-VDAT NVIDIA ConnectX-6 Dx EN Dual-Port 25GbE SFP56 PCIe 4.0 x16 Ethernet Network Adapter
MCX623106AN-CDAT NVIDIA ConnectX-6 Dx EN Dual-Port 100GbE QSFP56 PCIe 4.0 x16 Ethernet Network Adapter
Storage
- Dell Unity XT 380F 2U rack
- Dell Unity XT 380XT 2U rack
- Dell Unity XT 480F 2U rack
- Dell Unity XT 480XT 2U rack
- Dell Unity XT 680F 2U rack
- Dell Unity XT 680XT 2U rack
Optics
- MMA1T00-HS NVIDIA HDR 200Gb/s QSFP56 MPO Optical Transceiver
- MMA4Z00-NS NVIDIA NDR 400Gb/s OSFP Optical Transceiver
- QSFP-100G-SR4 Arista 100GBASE-SR4 QSFP28 Optical Transceiver
Hyperconverged cluster
Plan at least two 25GbE ports per node to two switches; all-NVMe clusters often move to 100GbE.
HCI nodes
HPE SimpliVity 325 Gen10 1U rack
HPE SimpliVity 380 Gen10 G 2U rack
HPE SimpliVity 325 Gen10 Plus v2 1U rack
Lenovo ThinkAgile VX650 V2 2U rack
Adapters for the server
- MBF2H516C-CESCOT NVIDIA BlueField-2 DPU Dual-Port 25GbE SFP28 16GB Arm Crypto PCIe 4.0 x8 Data Processing Unit
- MCX512A-ACAT NVIDIA ConnectX-5 EN Dual-Port 25GbE SFP28 PCIe 3.0 x8 Low-Profile Ethernet Network Adapter
- MCX623105AN-VDAT NVIDIA ConnectX-6 Dx EN Dual-Port 25GbE SFP56 PCIe 4.0 x16 Ethernet Network Adapter
- MCX623106AN-CDAT NVIDIA ConnectX-6 Dx EN Dual-Port 100GbE QSFP56 PCIe 4.0 x16 Ethernet Network Adapter
Optics
- MMA1T00-HS NVIDIA HDR 200Gb/s QSFP56 MPO Optical Transceiver
- MMA4Z00-NS NVIDIA NDR 400Gb/s OSFP Optical Transceiver
- QSFP-100G-SR4 Arista 100GBASE-SR4 QSFP28 Optical Transceiver
Plan and size it
- Draw this setup in the topology planner mrplanb.com
- Add up rack power and space rack-density.com
- iSCSI explained mrplanb.com
- Virtualization storage Ledger: scored storage platforms mrplanb.com
- Network monitoring tools compared mrplanb.com
Check compatibility with NVIDIA
Before you buy, confirm the exact configuration against the vendor's own lists: firmware levels, operating systems, adapters and optics that NVIDIA has tested with the NVIDIA Spectrum-2 SN3420.
- Compatibility NVIDIA Qualified System Catalog (certified GPU servers)
- Specifications NVIDIA Networking documentation (adapters, switches, cables)
- Support NVIDIA Enterprise Support
Equivalent models from other brands
FAQ
What is NVIDIA WJH telemetry?
What Just Happened (WJH) provides real-time, hardware-level diagnostic data on dropped packets and buffer congestion.
How many 100GbE uplinks are on the SN3420?
It features 12 dedicated 100GbE QSFP28 ports, offering higher uplink bandwidth than the 8-port SN2410.
Buying or selling Spectrum-2 SN3420?
New, refurbished or used. Tell us the quantity and condition and we connect you with a vetted reseller in your region, usually within one working day.
Sources
- NVIDIA Spectrum-2 SN3420 Product Overview, checked 2026-10-27
- NVIDIA Spectrum-2 SN3420 Datasheet, checked 2026-10-27