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Mellanox ConnectX‑4 Lx EN MCX4121A‑ACAT Dual‑Port 25GbE SFP28 Ethernet Adapter Card
Product Details:
| Brand Name: | Mellanox |
| Model Number: | MCX4121A-ACAT |
| Document: | connectx-4-lx-en-card.pdf |
Payment & Shipping Terms:
| Minimum Order Quantity: | 1pcs |
|---|---|
| Price: | Negotiate |
| Packaging Details: | outer box |
| Delivery Time: | Based on inventory |
| Payment Terms: | T/T |
| Supply Ability: | Supply by project/batch |
|
Detail Information |
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| Application: | Server | Interface Type:: | Network |
|---|---|---|---|
| Ports: | Dual | Max Speed: | 25GbE |
| Connector Type: | SFP28 | Type: | Wired |
| Condition: | New And Original | Model: | MCX4121A-ACAT |
| Name: | Mellanox Network Card ConnectX-4 Lx EN 25GbE Dual-Port SFP28 PCIe3.0 X8 Network Interface Card MCX4121A-ACAT | Keyword: | Mellanox Network Card |
Product Description
Mellanox ConnectX-4 Lx EN
MCX4121A-ACAT Dual-Port 25GbE Adapter
High-performance 2x25GbE SFP28 network interface card with RoCE, SR-IOV, and overlay hardware offloads for modern data centers.
per port
RoCE | RDMA | SR-IOV
Product Overview
The Mellanox ConnectX-4 Lx EN MCX4121A-ACAT is a dual-port 25 Gigabit Ethernet adapter card designed to meet the rigorous demands of virtualized infrastructures, cloud platforms, big data analytics, and storage environments. Offering a flexible combination of 25GbE, 10GbE, and 1GbE speeds on each SFP28 port, this PCIe 3.0 x8 adapter delivers high message rate (75 million packets per second) and sub‑microsecond latency. With native hardware support for RoCE (RDMA over Converged Ethernet), overlay network offloads (VXLAN, NVGRE, GENEVE), and Mellanox Multi-Host technology options in the series, the MCX4121A-ACAT dramatically reduces CPU overhead while maximizing server efficiency.
Built for enterprise, finance, healthcare, and hyperscale data centers, this card ensures reliable hardware-based I/O virtualization and advanced QoS – enabling higher consolidation ratios and lower total cost of ownership.
Key Performance Features
- Dual-port SFP28 supporting 25GbE / 10GbE / 1GbE speeds
- PCI Express 3.0 x8 (compatible with Gen1/Gen2)
- Sub‑microsecond latency & 75Mpps message rate
- RDMA over Converged Ethernet (RoCE) for low-latency access
- Hardware offload for NVGRE, VXLAN, GENEVE overlays
Virtualization & Acceleration
- SR-IOV: up to 256 Virtual Functions (VFs)
- Advanced QoS and traffic isolation
- Mellanox PeerDirect® (GPUDirect®) for GPU‑centric acceleration
- Stateless TCP/UDP offloads: LSO, LRO, checksum, RSS
- End‑to‑end congestion control & IEEE DCB support
Advanced Technology
RoCE & RDMA: The ConnectX-4 Lx EN implements RDMA over Converged Ethernet (RoCE) allowing direct memory access between servers with minimal CPU intervention – critical for distributed storage, NVMe over Fabrics, and high-frequency trading environments.
Overlay Network Acceleration: Data center operators rely on VXLAN and NVGRE to scale cloud networks. This adapter performs encapsulation/decapsulation in hardware, preserving native performance and freeing host processors.
Hardware-based I/O Virtualization: By supporting SR-IOV, the MCX4121A-ACAT delivers dedicated adapter resources per virtual machine, ensuring guaranteed isolation and predictable performance in multi-tenant environments.
Mellanox PeerDirect®: Eliminates unnecessary data copies between CPU and GPU, reducing application runtime for AI/ML and high-performance computing workloads.
Typical Deployments
- ✔️ Hyper‑converged infrastructure (HCI) nodes
- ✔️ Software‑defined storage (Ceph, vSAN, Lustre)
- ✔️ Cloud & OpenStack compute hosts
- ✔️ AI/GPU clusters with GPUDirect support
- ✔️ Database and big data analytics (Spark, Hadoop)
- ✔️ Financial trading platforms requiring ultra-low latency
Compatibility & Ecosystem
MCX4121A-ACAT supports mainstream operating systems and hypervisors:
- Linux: RHEL/CentOS, Ubuntu, Debian, OpenFabrics OFED
- Windows Server: 2016/2019/2022 (WinOF-2 drivers)
- Virtualization: VMware ESXi, KVM, Citrix XenServer, Microsoft Hyper-V
- Other: FreeBSD, OpenBSD
Interoperable with 1/10/25/40/50GbE switches (IEEE standards), passive copper cables up to 5m, active optical cables, and SFP28 optical modules. Backward compatible with 10GbE and 1GbE infrastructure.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | MCX4121A-ACAT |
| Ports | 2x SFP28 |
| Supported Speeds | 25GbE / 10GbE / 1GbE per port |
| Host Interface | PCIe 3.0 x8 (upward/downward compatible to PCIe 2.0/1.1) |
| Form Factor | Low-profile PCIe (with full-height bracket included) |
| Latency | Sub‑microsecond |
| Message Rate | 75 Million packets per second (75Mpps) |
| Hardware Offloads | RoCE, VXLAN/NVGRE/GENEVE encap/decap, TSO/LRO, checksum offload, RSS |
| Virtualization | SR-IOV (up to 256 VFs), VMware NetQueue, QoS per VM |
| Management Interfaces | NC-SI over MCTP (SMBus/PCIe), BMC interface, SPI flash, JTAG |
| Remote Boot | PXE, UEFI, iSCSI boot over Ethernet |
| Dimensions (Low-profile) | 14.2cm x 6.9cm (without bracket) |
| Power Consumption | Not publicly specified – typical < 12W; confirm per system load |
| Standards Compliance | IEEE 802.3by, 802.3ba, 802.3ae, 802.1Qbb, 802.1Qaz, PCIe 3.0, RoHS |
Selection Guide – ConnectX-4 Lx EN Family
| Ordering Part Number (OPN) | Ports & Speed | Interface | Form Factor | Special Notes |
|---|---|---|---|---|
| MCX4121A-ACAT | 2x 25GbE | SFP28 | PCIe low-profile | UEFI enabled, standard bracket included |
| MCX4111A-ACAT | 1x 25GbE | SFP28 | PCIe low-profile | Single port |
| MCX4131A-GCAT | 1x 50GbE | QSFP28 | PCIe low-profile | 50/40/25/10/1GbE support |
| MCX4421A-ACAN | 2x 25GbE | SFP28 | OCP 2.0 Type 1 | Host management |
| MCX4431M-GCAN | 1x 50GbE | QSFP28 | OCP 2.0 Type 2 | Multi-Host Technology |
* For Multi-Host configurations or OCP 3.0 version (MCX4621A-ACAB), please contact our team.
Why Choose Starsurge for ConnectX-4 Lx EN
- Engineering-grade sourcing: Genuine Mellanox original cards, full traceability.
- Global delivery: Fast shipping to Americas, Europe, APAC with customs support.
- Pre‑sales technical consulting: Our certified engineers help you verify server compatibility and configuration.
- Competitive pricing for volume projects: Special pricing for data center rollouts and system integrators.
- Warranty & after-sales support: Standard 1-year warranty, extended options available.
Service & Support
Technical Support: 24-hour ticket system and live chat during business hours (GMT+8). Firmware updates, compatibility matrices, and driver packages available upon request.
RMA Process: Advanced replacement options for qualified customers. Standard RMA: 7-14 business days.
Custom labeling & bulk packaging: Available for OEM/ODM partners.
Frequently Asked Questions
A: Yes, this card works in most x86 servers with PCIe 3.0 x8 slots. Please ensure a standard SFP28 cage and proper airflow. We recommend checking BIOS settings for SR-IOV enablement.
A: The dual SFP28 ports operate as independent 25G interfaces. For 25G to 4x10G breakout, use compatible switch side; the card itself does not break out a single port to multiple lanes.
A: MCX4121A-XCAT supports 10/1GbE only (max 10GbE), while the -ACAT version additionally supports 25GbE speeds. Choose -ACAT for future 25G readiness.
A: Yes, it supports passive SFP28 copper cables up to 5 meters, as well as active optical cables and optical transceivers.
A: Yes, request a quote with your quantity for customized pricing.
Precautions & Notes
- Ensure server motherboard provides adequate airflow for 25G operation in high ambient temperature.
- Please confirm PCIe slot bifurcation if using multiple adapters; the card uses x8 lane width.
- Firmware updates must be performed using Mellanox/NVIDIA tools; improper flashing may void warranty.
- Specifications not explicitly listed (e.g., maximum power consumption) are subject to engineering verification; please contact Starsurge for specific integration support.
About Hong Kong Starsurge Group Co., Limited
Founded in 2008, Starsurge is a technology-driven provider of network hardware, IT services, and system integration solutions. We serve government, healthcare, manufacturing, education, finance, and enterprise clients worldwide. Backed by an experienced sales and technical team, Starsurge offers IoT solutions, network management systems, custom software development, multilingual support, and global delivery. Our customer-first approach focuses on reliable quality, responsive service, and tailored solutions that help clients build efficient, scalable network infrastructures.
As an official partner for leading brands, Starsurge supplies genuine Mellanox/NVIDIA adapters with full traceability, competitive pricing, and dedicated pre/post-sales engineering support.
Key Facts
- ✅ Dual 25GbE ports – line rate performance
- ✅ RoCE & RoCE v2 capable
- ✅ Up to 256 SR-IOV virtual functions
- ✅ Hardware offload for overlay tunnels
- ✅ Low profile + full-height bracket included
Compatibility Matrix (Quick Check)
| Vendor | Server Models (Tested) |
|---|---|
| Dell | PowerEdge R740/R750/R6515 |
| HPE | DL380 Gen10/Gen11, DL360 |
| Supermicro | X11/X12 series with PCIe 3.0 slot |
| Cisco | UCS C220 M5/M6 |
Buyer Checklist
- ☑️ Confirm server has an available PCIe x8 (or x16) slot
- ☑️ SFP28 optics or DAC length suited for your cabling distance
- ☑️ Operating system driver version (OFED / WinOF-2) ready
- ☑️ For RDMA, ensure DCB configuration on switchesRelated Products
- MCX4111A-ACAT – Single-port 25GbE, same silicon
- MCX4131A-GCAT – Single-port 50GbE QSFP28
- Mellanox MFA1A00-E005 – 25G SFP28 active optical cable
- MMA1B00-C100D – 25GBase-SR SFP28 transceive