Identity & Definition
The NVIDIA Mellanox MCX556N-EDAT is a 100Gb/s enterprise VPI (Virtual Protocol Interconnect) network adapter in refurbished condition. This dual-port QSFP28 adapter is based on Mellanox ConnectX-5 Ex technology and supports both InfiniBand EDR (100Gb/s) and 100GbE Ethernet per port, configurable via firmware. The MCX556N-EDAT features Socket Direct technology with an integrated PCIe switch for multi-host and NUMA-optimized deployments. It ships with a full-height (tall) bracket.
Engineering Context
The MCX556N-EDAT delivers 100Gb/s per port (200Gb/s aggregate) through its two QSFP28 ports using four lanes of 25Gb/s NRZ signaling per port. The adapter connects to the host via a PCIe 4.0 x8 interface with an integrated PCIe switch that enables Socket Direct — allowing direct attachment to multiple CPU sockets for NUMA-aware networking. ConnectX-5 Ex VPI supports SR-IOV (up to 1024 VFs), RoCE v2, GPUDirect RDMA, DPDK acceleration, VXLAN/NVGRE/Geneve tunnel offload, TLS inline encryption, and hardware-based flow steering.
Deployment & Use Cases
The MCX556N-EDAT is deployed in dual-socket servers requiring NUMA-optimized high-bandwidth networking. Typical use cases include HPC clusters using EDR InfiniBand for MPI and GPU-to-GPU RDMA workloads, 100GbE storage fabric connections for NVMe-oF and parallel file systems (Lustre, GPFS, BeeGFS), AI/ML training nodes requiring GPUDirect RDMA with NUMA locality, and multi-tenant cloud environments requiring VPI flexibility to switch between IB and Ethernet protocols per workload.
Technical Specifications

Part Number (MPN): MCX556N-EDAT
Adapter Family: ConnectX-5 Ex VPI
Adapter Type: VPI (InfiniBand + Ethernet)
Port Count: 2 (Dual-Port)
Port Type: QSFP28
Data Rate: 100Gb/s per port (200Gb/s aggregate)
Host Interface: PCIe 4.0 x8 (with PCIe Switch)
Form Factor: Full-Height (Tall Bracket) PCIe Add-in Card
Special Features: Socket Direct, Integrated PCIe Switch
Protocols: EDR IB, 100GbE, RoCE v2, SR-IOV, GPUDirect RDMA, DPDK
Condition: Refurbished

Compatibility & Hard Constraints
The MCX556N-EDAT requires a PCIe 4.0 or PCIe 3.0 x8 or wider slot (PCIe 4.0 recommended for full bandwidth). The Socket Direct feature requires a dual-socket server with compatible BIOS support for multi-host PCIe device assignment. The QSFP28 ports accept 100GbE QSFP28 transceivers, 100GbE QSFP28 DAC cables, EDR InfiniBand cables, or QSFP28-to-4xSFP28 breakout cables. It is NOT a standard ConnectX-5 — the "Ex" designation and "N" suffix indicate the extended Socket Direct variant. For a non-Socket-Direct dual-port EDR VPI, consider the MCX556A-ECAT.
Why Choose T.E.S IT-SOLUTIONS
Every MCX556N-EDAT adapter sold by T.E.S IT-SOLUTIONS is functionally tested and verified before shipment. Our team provides technical consultation on NVIDIA Mellanox VPI adapter compatibility, Socket Direct configuration, and deployment planning. Orders ship within 1–3 business days with worldwide delivery and protective packaging.