Network adapter Mellanox Technologies MCX4121A-ACAT internal PCI Express fiber interface

Internal network adapter Mellanox Technologies MCX4121A-ACAT with a PCI Express host interface and fiber connectivity provides a high-performance fiber optic link for servers and workstations. Based on the ConnectX-4 Lx EN family, this card supports multi-rate Ethernet from 1 Gb/s up to 50 Gb/s and is designed for wired network environments where fiber connections and low-latency, high-throughput links are required. The adapter implements RDMA acceleration and hardware offloads to reduce CPU overhead and improve overall application efficiency in virtualized and storage-heavy deployments.

Advantages

The MCX4121A-ACAT delivers flexible multi-rate Ethernet (1/10/25/40/50 Gb/s) on a single interface and includes support for RDMA and overlay network encapsulation/decapsulation to optimize data path performance. Using a PCI Express host connection and fiber physical interface, the adapter provides improved I/O isolation, reduced latency, and hardware-based offloads that lower CPU utilization for data center, cloud and analytics workloads. Its design targets scalability and compatibility with common server platforms for deployments that require reliable fiber links.

Suitable for

• High-throughput data center networking and spine/leaf fabrics
• Storage systems and SAN connectivity that require fiber optics
• Virtualized servers and cloud infrastructure with heavy east–west traffic
• Database and analytics platforms demanding low latency and high I/O
• Environments using RDMA for accelerated data transfers

Key specifications

• Host interface: PCI Express (x8 or compatible slot)
• Physical interface: fiber optic transceiver (SFP+/QSFP-compatible form factor depending on module)
• Supported link rates: 1 Gb/s, 10 Gb/s, 25 Gb/s, 40 Gb/s, 50 Gb/s
• Controller family: ConnectX-4 Lx EN
• Offload features: RDMA, hardware-based overlay encapsulation/decapsulation
• Optimized for virtualized and cloud workloads with hardware I/O isolation

How to use

Install the Mellanox MCX4121A-ACAT into an available PCI Express slot on a compatible server or workstation following the host platform vendor’s procedures. Equip the card with the appropriate fiber transceiver module and connect to the fiber network using suitable fiber cabling and connectors. Install Mellanox drivers and firmware recommended for the server operating system to enable full feature support including RDMA and offload capabilities. Configure network settings, link speed, and driver parameters according to your environment and management tools.

Usage recommendations

Select fiber transceivers and cabling that match the supported link rates and the data center infrastructure. Keep firmware and drivers up to date to ensure compatibility and performance. For RDMA and high-performance workloads, verify server BIOS and OS settings (such as interrupt moderation and SR-IOV if applicable) to maximize throughput and reduce latency.