NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card

The NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card is a high-performance dual-port NIC designed to accelerate networking for servers, workstations, and data centers. Built on PCI Express 3.0 x8, this plug-in card delivers 2 x 25GBASE-R ports via SFP28 optics, enabling fiber-based connectivity that scales seamlessly with demanding workloads. From dense virtualization environments to data-intensive storage networks, the ConnectX-4 Lx EN is engineered to maximize throughput, reduce latency, and lower CPU overhead so your applications can run faster and more efficiently. Whether you’re deploying a GPU-accelerated server, a high-performance compute node, or a storage gateway, this NIC is designed to meet the rigorous requirements of modern IT infrastructure with reliability and flexibility.

Designed for the realities of real-world deployments, the ConnectX-4 Lx EN brings hardware offloads and advanced networking features that translate to tangible performance gains. Offloading common networking tasks from the CPU frees up processor cycles for application logic, data processing, and analytics. The result is lower latency, higher sustained throughput, and improved efficiency under heavy load. The dual 25GBASE-R ports are ideal for scalable, fault-tolerant networks, enabling quick patching, rapid failover, and straightforward link aggregation when your workloads demand peak bandwidth. In addition, the SFP28 interfaces offer flexible fiber options, enabling long-reach connectivity and future-ready upgrades without swapping cards. This makes the ConnectX-4 Lx EN a solid choice for data centers pursuing performance optimization, virtualization, and high-bandwidth storage access.

Key deployment scenarios include acceleration of distributed databases, high-speed data replication, AI inference pipelines, software-defined networking, and virtualized environments running multiple tenants. The card’s robust feature set supports virtualization technologies such as SR-IOV, which enables near-native performance for virtual machines, while providing strong isolation between workloads. For enterprises embracing microservices and containerized workloads, the CUDA-enabled hardware acceleration ecosystem and advanced NIC features help reduce network latency, streamline service-to-service communication, and ensure consistent performance as demand evolves. With two 25G ports and flexible SFP28 fiber connectivity, you gain the bandwidth headroom required for modern, data-driven workflows while maintaining compatibility with existing switches and fiber infrastructures.

• Dual 25GBASE-R ports with SFP28 optics deliver up to 50 Gbps of aggregate bandwidth per card and flexible fiber connectivity for scalable data-center networks.
• PCIe 3.0 x8 host interface provides ample PCIe bandwidth to sustain high-speed I/O without saturating the bus, helping to keep CPU overhead low during heavy networking tasks.
• Optical fiber compatibility via SFP28 connectors enables long-reach, high-density deployments while preserving flexibility for future fiber upgrades and dynamic topologies.
• Advanced offloads and virtualization including hardware offload for TCP/IP, RDMA (RoCE v2), VXLAN/NVGRE, and SR-IOV support to maximize throughput, reduce latency, and improve multitenant scalability.
• OCP 3.0 bracket compatibility and plug-in card form factor simplify installation in modern servers, blades, and workstation platforms while supporting easy integration into existing chassis layouts.

Technical Details of NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card

• Model: NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card
• Network interfaces: 2 x 25GBASE-R ports (SFP28)
• Host interface: PCI Express 3.0 x8
• Bracket: OCP 3.0 bracket height compatible
• Form factor: Plug-in PCIe card
• Connectivity type: Optical fiber via SFP28 modules
• Performance: Up to 25 Gbps per port; up to 50 Gbps aggregate bandwidth with dual-port operation
• Offloads and features: Hardware offload for TCP/IP, UDP, RDMA (RoCE v2), VXLAN/NVGRE, and other advanced networking tasks; virtualization support including SR-IOV
• Performance optimization: Reduced CPU overhead, lower latency, improved multi-queue and interrupt handling for high-throughput workloads
• Driver and compatibility: Typically supports Linux and Windows environments with NVIDIA/Mellanox driver stacks; designed for enterprise and data-center deployments

How to Install NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card

Installing the ConnectX-4 Lx EN is straightforward for experienced administrators. Follow these steps to ensure a proper and stable deployment:

• Power down the server and unplug all power sources. Ground yourself to avoid static discharge before handling the NIC.
• Open the server chassis and locate an available PCI Express slot that accommodates an x8 or higher card. Confirm there is adequate clearance for the OCP 3.0 bracket height and that the system’s BIOS/UEFI supports PCIe passthrough if you plan to use virtualization.
• Insert the ConnectX-4 Lx EN card firmly into the chosen PCIe x8 slot. Secure the card with the retaining screw or bracket mounting hardware as required by your chassis.
• Attach the optical fiber transceivers (SFP28 modules) to the two 25GBASE-R ports and connect the corresponding fiber cables to your switch or fabric, ensuring correct link polarity and distance per the transceiver specifications.
• Power on the server and install the latest NVIDIA/Mellanox drivers. Download the appropriate driver package for your operating system, then follow the installer prompts to complete the NIC installation and firmware updates if available.
• In the operating system, verify the device is detected (for example, via lspci on Linux or Device Manager on Windows). Check that the two 25G NIC interfaces appear as expected and that the link status shows active.
• Configure network interfaces, VLANs, bonding or teaming, and any required offload features (SR-IOV, RDMA, VXLAN, etc.) according to your workload needs. Validate connectivity with basic tests (ping, iperf, and throughput tests) to ensure the expected performance and stability.

Frequently asked questions

• What is the NVIDIA ConnectX-4 Lx EN 25Gigabit Ethernet Card? A high-performance, dual-port 25GbE NIC designed for servers and workstations, offering fiber connectivity through SFP28 and a PCIe 3.0 x8 interface with advanced offloads and virtualization features.
• How many ports does it have? It features two 25GBASE-R ports (dual-port) using SFP28 connectors for flexible fiber deployment.
• What kind of fiber connectors does it use? SFP28 optical fiber modules are used for 25GBASE-R connectivity; you will need compatible SFP28 transceivers and cables for your network.
• What deployment scenarios benefit from this card? Data centers, virtualization hosts, storage gateways, AI/ML inference servers, and high-throughput compute nodes that require high-bandwidth networking with low CPU overhead.
• Does it support virtualization and RDMA? Yes. It includes hardware offloads and virtualization features, including SR-IOV and RDMA (RoCE v2), to improve performance in virtualized and multi-tenant environments.
• Is driver support available for Linux and Windows? NVIDIA/Mellanox provides driver support for common server OS environments, including Linux and Windows, to enable full functionality of the 25G NIC features.
• How do I verify the NIC is functioning correctly after installation? Check link status with ethtool or ifconfig (Linux) or corresponding tools on Windows, perform basic throughput tests (e.g., iperf), and confirm that both ports are recognized by the OS and switch fabric.