NVIDIA Mellanox® MCX4111A-ACAT — ConnectX-4 Lx EN Single-Port 25GbE SFP28 Adapter

Technical Identity
The NVIDIA Mellanox® MCX4111A-ACAT is a single-port 25 Gigabit Ethernet network adapter built on the ConnectX-4 Lx (Light) ASIC. The Lx silicon is the Ethernet-only member of the ConnectX-4 family — it does not run InfiniBand and is not VPI. The card uses one SFP28 cage and a PCIe 3.0 x8 host interface in a standard low-profile PCIe form factor, sealed new in original NVIDIA / Mellanox packaging.

Specifications

OEM: NVIDIA Mellanox
Part Number (MPN): MCX4111A-ACAT
Product family: ConnectX-4 Lx EN (Ethernet NIC)
ASIC / Generation: ConnectX-4 Lx
Ports: 1× SFP28
Line rate: 25GbE (backward compatible 10/1GbE)
Protocol: Ethernet only (Lx ASIC — no InfiniBand, no VPI)
Host interface: PCIe 3.0 x8 (8.0 GT/s per lane)
Form factor: Standard low-profile PCIe card
Condition: New, factory-sealed


What This Is NOT

NOT VPI / dual-protocol. The Lx ASIC is Ethernet-only; this card cannot operate as an InfiniBand HCA.
NOT a dual-port adapter. MCX4111A is single-port; the dual-port SFP28 sibling is MCX4121A-ACAT.
NOT a 100GbE card. The SFP28 cage and Lx ASIC top out at 25GbE per port.
NOT a ConnectX-5/6/7. Driver, firmware, and feature set are ConnectX-4 Lx specific.
NOT a switch or transceiver. Host-side PCIe NIC — requires a server PCIe 3.0 x8 (or wider) slot.
NOT bundled with SFP28 cables, transceivers, or extra brackets.


Compatibility & Constraints

Drivers: NVIDIA MLNX_OFED / MLNX_EN for Linux, upstream in-box mlx5_core, WinOF-2 for Windows Server, nmlx5 for VMware ESXi.
Host slot: PCIe 3.0 x8 minimum at full lane width to sustain 25Gb/s line rate. PCIe 2.0 or x4 slots will throttle throughput.
Cabling: SFP28 25GbE DAC, AOC, or optical transceivers (SR / LR). SFP+ 10GbE modules are accepted in the SFP28 cage for backward-compatible 10GbE links.
Compatible switches (pairs with — not a category): NVIDIA Spectrum / Spectrum-2 Ethernet switches (MSN21xx / MSN27xx / MSN24xx / MSN37xx series) at 25GbE. Also interoperable with standard 25GbE Ethernet switches from Cisco, Arista, Dell, and HPE running 25GBASE-CR / SR / LR.
Offloads & features: RoCE v1/v2 RDMA, SR-IOV (up to 256 VFs), ASAP² hardware-accelerated Open vSwitch, VXLAN / NVGRE / Geneve / GTP encapsulation, T10-DIF, NVMe-oF over RoCE v2, PXE / UEFI boot.
Cooling / power: Standard PCIe slot power; passive heatsink — adequate chassis airflow required.


Deployment & Use Cases

25GbE leaf-to-server connectivity in Spectrum-based Ethernet fabrics.
RoCE v2 transport for NVMe-oF storage initiators and targets.
SR-IOV virtualization in KVM / VMware / Hyper-V hosts.
SDN / NFV servers using OVS hardware offload (ASAP²).
Cost-efficient Ethernet front-end for HPC / analytics servers that do not need full ConnectX-4 VPI features.


Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCX4111A-ACAT?
The MCX4111A-ACAT is a single-port 25GbE SFP28 ConnectX-4 Lx EN network adapter with a PCIe 3.0 x8 host interface. It is Ethernet-only (Lx ASIC) and ships new, factory-sealed.
Q. Does the MCX4111A-ACAT support InfiniBand?
No. ConnectX-4 Lx is an Ethernet-only ASIC and cannot operate as an InfiniBand HCA. For VPI / InfiniBand, use a ConnectX-4 (non-Lx) part such as MCX4131A-BCAT/GCAT or a ConnectX-5/6 VPI card.
Q. What drivers does this adapter require?
NVIDIA MLNX_OFED or MLNX_EN for Linux, in-box mlx5_core in upstream Linux kernels, WinOF-2 for Windows Server, and nmlx5 for VMware ESXi.
Q. What switches and cables are compatible with MCX4111A-ACAT?
Pairs with NVIDIA Spectrum / Spectrum-2 25GbE Ethernet switches and with standard 25GbE Ethernet switches from other vendors. Cabling: SFP28 DAC, AOC, or 25G SR/LR optical transceivers; SFP+ 10G modules are accepted for backward-compatible 10GbE links.
Q. Is this a new or refurbished unit?
New, factory-sealed unit in original NVIDIA / Mellanox packaging, supplied from T.E.S IT-SOLUTIONS EU stock.

Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based NVIDIA Mellanox specialist serving HPC, AI, and enterprise data-center procurement teams since 2007. Every adapter is identified by MPN, NVIDIA P/N, and ASIC generation before shipment; pre-sale compatibility advice for switch / adapter / cable pairing is included at no extra cost. Multi-currency B2B invoicing, EU stock with worldwide express options, and direct technical contact with our engineering team — not a call-center.