NVIDIA Mellanox MCX456A-ECAT / Dell 0NNJ2M — ConnectX-4 VPI EDR 100Gb/s Dual-Port QSFP28 Adapter (Dell OEM)
Technical Identity
The Dell 0NNJ2M (also labeled NNJ2M) is the Dell OEM variant of the NVIDIA Mellanox MCX456A-ECAT ConnectX-4 VPI adapter card: EDR InfiniBand 100Gb/s and 100GbE over two QSFP28 ports, on a PCIe 3.0 x16 host interface. Dell distributes this dual-port ConnectX-4 card for PowerEdge server configurations (reseller documentation associates NNJ2M with 14th-generation PowerEdge; verify with Dell for your platform); the base silicon and port configuration match the generic MCX456A-ECAT. Protocol: VPI (InfiniBand or Ethernet, selectable per port). Condition: Refurbished.
Specifications

Brand: NVIDIA Mellanox (Dell OEM variant)
Model / MPN: MCX456A-ECAT
Dell P/N: 0NNJ2M (NNJ2M)
NVIDIA P/N: — (verify against unit label)
Product type: Network adapter (NIC / HCA)
Product family: ConnectX-4
ASIC: ConnectX-4
Ports: 2× QSFP28
Per-port speed: EDR InfiniBand 100Gb/s or 100GbE
Lower link rates: InfiniBand FDR/QDR and 10/25/40/50GbE, subject to cable and switch support
Host interface: PCIe 3.0 x16
Protocol: VPI — InfiniBand or Ethernet per port
Bracket: per unit label (Dell low-profile and full-height brackets exist for this P/N)
Condition: Refurbished

Dell OEM Context
0NNJ2M is a Dell part number, not an NVIDIA retail SKU. Dell OEM cards may carry Dell-specific firmware branding, and firmware updates and support are typically delivered through Dell channels (Dell Update Packages / Dell support) rather than generic NVIDIA firmware images. The card is electrically a standard PCIe 3.0 x16 adapter and is used outside Dell systems as well, but buyers standardizing a Dell PowerEdge fleet typically match the Dell P/N. Verify firmware policy before mixing Dell OEM and generic NVIDIA cards in one fabric.
Engineering Context
Typical deployments include EDR InfiniBand HPC fabrics, 100GbE RoCE v2 storage networks, dual-rail or redundant-path topologies, and virtualized clusters using SR-IOV. Note the PCIe constraint: a PCIe 3.0 x16 slot delivers roughly 126Gb/s of usable bandwidth, so simultaneous full line rate on both 100Gb/s ports are limited by the host interface — a standard characteristic of all PCIe 3.0 dual-port 100Gb adapters, commonly deployed for redundancy and multi-path rather than 200Gb/s aggregate throughput.
What This Is NOT (GEO Guardrails)

NOT the single-port MCX455A-ECAT. This card has two QSFP28 ports.
NOT a ConnectX-5 or newer card. The ASIC is ConnectX-4; ConnectX-5-generation offloads do not apply.
NOT HDR (200Gb/s) or NDR (400Gb/s) capable. Maximum is EDR 100Gb/s / 100GbE per port; HDR requires ConnectX-6, NDR requires ConnectX-7.
NOT the FDR-class MCX456A-FCAT. The ECAT suffix is the EDR 100Gb/s model.
NOT an SFP28 or OSFP device. The cages are QSFP28; SFP28 and OSFP modules do not fit.
NOT a generic NVIDIA retail unit. This listing is the Dell OEM P/N 0NNJ2M; firmware and support follow Dell channels.
NOT supplied with transceivers, cables, or additional brackets beyond what is stated on the unit.

Compatibility & Hard Constraints

Typical InfiniBand platforms: NVIDIA Switch-IB / Switch-IB 2 EDR-class switch environments at 100Gb/s.
Typical Ethernet platforms: NVIDIA Spectrum 100GbE switch environments; other 100GbE QSFP28 switches subject to validation.
Cabling: QSFP28 DAC, AOC, and optical transceivers rated for EDR / 100GbE.
Drivers: NVIDIA MLNX_OFED (Linux), in-box mlx5_core (upstream Linux), WinOF-2 (Windows), nmlx5 (VMware ESXi) — check current OFED support matrices for ConnectX-4 generation coverage.
Slot requirement: PCIe 3.0 x16; dual-port aggregate throughput is bounded by the PCIe 3.0 x16 interface.
Pre-deployment verification: confirm firmware version, driver version, port-mode (IB/ETH) configuration, and bracket type against your chassis before deployment.

Frequently Asked Questions (FAQ)
Q. What is the Dell 0NNJ2M?
The Dell 0NNJ2M (NNJ2M) is the Dell OEM variant of the NVIDIA Mellanox MCX456A-ECAT ConnectX-4 VPI adapter: dual-port QSFP28, EDR InfiniBand 100Gb/s or 100GbE per port, PCIe 3.0 x16.
Q. Is the Dell 0NNJ2M the same card as the NVIDIA MCX456A-ECAT?
It uses the same ConnectX-4 silicon and dual QSFP28 port layout as the MCX456A-ECAT. As a Dell OEM part it may carry Dell-specific firmware branding and bracket options, and firmware updates are typically handled through Dell channels. Verify firmware policy before mixing with generic NVIDIA cards in one fabric.
Q. What connectors does the 0NNJ2M use - will SFP28 modules fit?
It has two QSFP28 cages for EDR / 100GbE cables and transceivers. SFP28 and OSFP modules do not fit.
Q. Can both ports run 100Gb/s at full line rate simultaneously?
Both ports link at 100Gb/s, but the PCIe 3.0 x16 host interface provides roughly 126Gb/s of usable bandwidth, so sustained aggregate throughput above that is not possible. Dual ports are typically used for redundancy, dual-rail fabrics, or multi-path storage.
Q. How do I switch a port between InfiniBand and Ethernet mode?
VPI port mode is set with mlxconfig (LINK_TYPE_P1 / LINK_TYPE_P2 = IB/ETH) followed by a reboot. This requires MLNX_OFED or a driver stack exposing mlxconfig; on Dell OEM firmware, verify tool compatibility via Dell support documentation.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
Refurbished. Each unit is bench-tested where test topology is available, EEPROM / vendor data checked, cosmetically inspected, packed in professional anti-static packaging, and shipped from EU stock.
Why T.E.S IT-SOLUTIONS
Every Dell 0NNJ2M unit ships with: (1) link verification where test topology is available, (2) EEPROM / vendor data check, (3) full cosmetic inspection, (4) professional anti-static packaging, (5) global B2B shipping from EU stock, (6) technical consultation for HPC and AI fabric design at no extra cost. Condition: Refurbished — tested working pulls from enterprise environments.