Specifications
OPN / Part Number
MCX4121A-ACAT
Series
NVIDIA ConnectX-4 Lx
Ports
2 × 25GbE SFP28 (25/10/1G)
Data Rate
25 Gb/s per port, 50 Gb/s aggregate
Host Interface
PCIe 3.0 x8 (8 GT/s)
RDMA
RoCEv2
Packet Rate
Up to 75 Mpps
SR-IOV
Up to 256 virtual functions
Overlay Offload
VXLAN, NVGRE, GENEVE (stateless offloads)
Form Factor
PCIe half height, half length
Typical Power
≈ 12 W (dual 25G active)
Management
NC-SI, in-band
Compliance
RoHS, CE, FCC Class A
Target Market
Cost-sensitive 25G server access
Overview
ConnectX-4 Lx is the entry tier of NVIDIA's 25G Ethernet line: two SFP28 ports on a PCIe 3.0 x8 interface, with RoCEv2 and overlay offloads intact. It is the natural step up from 10G when a platform has PCIe 3.0 slots and budget is the binding constraint.
Because it shares the mlx5 driver family with ConnectX-5 through ConnectX-8, it can be mixed into a fleet of newer adapters without a separate driver stack — a practical advantage in large heterogeneous deployments.
Key Benefits
25G at low cost on PCIe 3.0 x8. RoCEv2 RDMA and overlay offloads. 256 VFs for virtualization. Shared mlx5 driver with the whole ConnectX family.
Applications
Cost-sensitive 25G server access, storage clients, virtualization hosts, Kubernetes worker nodes, and mixed-generation fleets standardising on the mlx5 driver.
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