NVIDIA Mellanox ConnectX-4 Lx EN MCX4621A-ACAB 25GbE Dual SFP28 OCP 3.0 NIC: This is an Ethernet network interface card built on the ConnectX-4 Lx ASIC in OCP 3.0 SFF form factor with a thumbscrew bracket. The card provides two SFP28 ports operating at 25GbE each over a PCIe 3.0 x8 host interface. This IS an OCP 3.0 mezzanine adapter; this is NOT a standard PCIe full-height/half-height card. This is a Refurbished unit.
Engineering Context
The ConnectX-4 Lx Lx-EN family targets cost-optimized 25GbE deployments and supports stateless TCP/UDP/IP offloads, RoCE v1/v2 for low-latency RDMA fabrics, and SR-IOV for hypervisor environments. PCIe 3.0 x8 provides ~63Gb/s of host bandwidth — adequate for two saturated 25GbE links. The OCP 3.0 SFF form factor enables hot-pluggable installation in compatible servers without opening the chassis. Dual-port SFP28 ports are backward compatible with 10GbE SFP+ optics and DACs at the slower negotiated rate.
Deployment & Use Cases
Cloud and hyperscale compute nodes requiring dual-25GbE Ethernet connectivity. OpenStack and VMware ESXi virtualization hosts with SR-IOV passthrough to guest VMs. Software-defined storage targets (Ceph, NVMe-oF over RoCE) where two 25GbE ports provide fault-tolerant fabric attachment. Edge and telco NFV workloads on OCP 3.0 servers (Open Compute, Wiwynn, Quanta).
Technical Specifications
OEM: NVIDIA Mellanox
Part Number (MPN): MCX4621A-ACAB
Controller / ASIC: ConnectX-4 Lx EN
Ports: 2x SFP28
Port Speed: 25GbE per port (also negotiates 10GbE/1GbE)
Host Interface: PCIe 3.0 x8
Form Factor: OCP 3.0 SFF
Bracket: Thumbscrew
RDMA: RoCE v1 & v2 supported
Virtualization: SR-IOV, stateless TCP/UDP/IP offloads
Compliance: RoHS
Condition: Refurbished — Tested by T.E.S IT-SOLUTIONS
Compatibility & Hard Constraints
Requires an OCP 3.0 SFF mezzanine slot — not installable in standard PCIe full-height/half-height slots without an OCP-to-PCIe carrier (not included). Compatible with NVIDIA Spectrum (SN2000) 25GbE switches and any standards-compliant 25GbE/10GbE Ethernet switch. Supports SFP28 25G DAC, SFP28 SR/LR optics, and SFP+ 10G DAC/optics in negotiated mode. Not InfiniBand-capable (Ethernet-only Lx variant). Driver support requires MLNX_OFED or upstream mlx5_core kernel module.
Why Choose T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS bench-tests every ConnectX adapter for link establishment, throughput, and PCIe enumeration before shipment. Visit tes-itsolutions.com for expert OCP 3.0 deployment consultation, 1–3 business day handling, global shipping, and warranty.