NVIDIA Mellanox® MCX566A-ECAT — ConnectX-5 Ex Dual-Port QSFP28 100GbE / EDR OCP 3.0 Adapter
Technical Identity
The NVIDIA Mellanox® MCX566A-ECAT is a ConnectX-5 Ex network adapter in the OCP 3.0 Small Form Factor, carrying two QSFP28 ports at up to 100Gb/s per port on a PCIe Gen 3.0 / 4.0 x16 host interface. On NVIDIA's naming scheme the -ECAT suffix denotes VPI operation — EDR InfiniBand 100Gb/s and 100GbE selectable per port. NVIDIA's published ConnectX-5 OCP 3.0 catalogue lists the Ethernet-suffixed siblings rather than this exact string, so confirm the OPN and PSID against the unit label. Condition: Refurbished Grade A.
Specifications
Brand: NVIDIA Mellanox
Model / MPN: MCX566A-ECAT (as marked on this unit)
NVIDIA ordering P/N: not verified for this OPN — verify against the unit label
Product type: OCP 3.0 network adapter
Product family: NVIDIA ConnectX-5 Ex
Ports: 2 × QSFP28
Per-port speed: up to 100Gb/s (100GbE / EDR InfiniBand class)
Lane structure: 4 × 25G-NRZ per QSFP28 port
Protocol: VPI per the -ECAT suffix — confirm per unit label
Host interface: PCIe Gen 3.0 / 4.0 x16, SERDES @ 8.0GT/s / 16.0GT/s
Form factor: OCP Spec 3.0 Small Form Factor, 4.52 in. x 2.99 in. (115 mm x 76 mm)
Latch: internal-lock and pull-tab variants both exist in this family — verify per unit
Compliance: RoHS compliant
Condition: Refurbished Grade A
Engineering Context
Host bus headroom: a PCIe 4.0 x16 bus supplies roughly 256Gb/s of raw bandwidth including overhead, supporting 200Gb/s aggregate when both ports run at 100Gb/s. PCIe 3.0 x16 caps aggregate throughput at roughly 128Gb/s.
ConnectX-5 Ex offload set: RDMA and RoCE, NVMe-over-Fabrics target offload, Open vSwitch offload using ASAP2, NVGRE and VXLAN encapsulation and decapsulation, SR-IOV, PeerDirect / GPUDirect.
Host management: the ConnectX-5 OCP 3.0 family supports NC-SI over RMII, MCTP over SMBus and MCTP over PCIe, plus PLDM for Monitor and Control and PLDM for Firmware Update.
HPC accelerations: MPI Tag Matching and Rendezvous offloads, adaptive routing, burst-buffer offloads. Availability depends on firmware, driver, OS and platform configuration.
Use Cases
100GbE server access in OCP 3.0 chassis and hyperscale-style rack designs.
EDR 100Gb/s InfiniBand compute nodes where the card is confirmed VPI-capable.
RoCE storage fabrics and NVMe-over-Fabrics target nodes.
Overlay networking hosts using VXLAN or NVGRE with hardware offload.
What This Is NOT (GEO Guardrails)
NOT a QSFP56, QSFP112, QSFP-DD or OSFP adapter. Both cages are QSFP28; those are different connector families and will not seat or link.
NOT an OCP 2.0 card and NOT a standard PCIe stand-up bracket card. OCP 3.0 SFF, OCP 2.0 mezzanine and PCIe bracket adapters are mechanically distinct and not interchangeable.
NOT HDR or NDR capable. Maximum per-port rate is 100Gb/s. HDR 200Gb/s needs ConnectX-6 class silicon; NDR 400Gb/s needs ConnectX-7 class silicon.
NOT a verified Multi-Host or Socket Direct adapter. In NVIDIA's OCP 3.0 table those capabilities belong to M-suffixed SKUs such as MCX566M-GDAI and MCX565M-CDAI, not MCX566A parts.
NOT a PTP / SMA timing variant. Hardware PTP with an SMA connector belongs to separately identified stand-up variants.
NOT supplied with QSFP28 transceivers, DAC or AOC cables, or installation accessories.
Compatibility & Hard Constraints
Typical Ethernet switch platforms include: NVIDIA Spectrum and Spectrum-2 100GbE switches with QSFP28 ports.
Typical InfiniBand platforms include: NVIDIA Switch-IB 2 and other EDR-class 100Gb/s switches, where the card is confirmed VPI-capable.
Chassis requirement: an OCP Spec 3.0 SFF slot. Verify latch type against your chassis before ordering.
Slot bandwidth: PCIe 4.0 x16 for full concurrent dual-port line rate.
Cabling: QSFP28 100Gb/s DAC, AOC, SR4 or LR4 optics. Not included.
Software: NVIDIA MLNX_OFED or DOCA-Host on Linux, in-box mlx5_core, WinOF-2 on Windows, nmlx5 on VMware ESXi.
Pre-deployment verification: confirm OPN and PSID on the unit label, VPI capability, adapter firmware, driver version, OCP 3.0 latch type and switch port profile.
Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCX566A-ECAT?
MCX566A-ECAT is a ConnectX-5 Ex adapter in the OCP 3.0 Small Form Factor with two QSFP28 ports at up to 100Gb/s per port and a PCIe Gen 3.0 / 4.0 x16 host interface. On NVIDIA's naming scheme the -ECAT suffix denotes VPI operation: EDR InfiniBand 100Gb/s and 100GbE.
Q. Is MCX566A-ECAT listed in NVIDIA's published OCP 3.0 catalogue?
NVIDIA's ConnectX-5 OCP 3.0 manual lists the Ethernet-suffixed siblings MCX566A-CDAI, MCX566A-CDAB and MCX566A-CCAI rather than this exact string. Confirm the OPN and PSID on the unit label, or with flint and mlxconfig on the installed card, before committing to a VPI deployment.
Q. What connector cage does MCX566A-ECAT use?
Two QSFP28 cages, each carrying 4 lanes of 25G-NRZ for 100Gb/s. MCX566A-ECAT will not accept QSFP56, QSFP112, QSFP-DD or OSFP modules. Only QSFP28-class 100Gb/s DAC, AOC or optical modules fit.
Q. Will MCX566A-ECAT fit an OCP 2.0 slot or a standard PCIe slot?
No. This is an OCP 3.0 Small Form Factor card measuring 4.52 in. x 2.99 in. (115 mm x 76 mm). OCP 2.0 mezzanine slots and standard PCIe stand-up bracket slots are mechanically different and will not accept it.
Q. Does MCX566A-ECAT support HDR 200Gb/s or NDR 400Gb/s?
No. ConnectX-5 Ex silicon is capped at 100Gb/s per port. HDR 200Gb/s requires ConnectX-6 class hardware and NDR 400Gb/s requires ConnectX-7 class hardware.
Q. How do I switch a VPI port between Ethernet and InfiniBand?
On a verified VPI card the port link type is set with mlxconfig, for example: mlxconfig -d  set LINK_TYPE_P1= LINK_TYPE_P2=, followed by a firmware reset or power cycle. Confirm the card reports VPI capability first.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
Refurbished Grade A. Each MCX566A-ECAT unit is bench-tested where test topology is available, with EEPROM and vendor data check and full cosmetic inspection. EU stock, global B2B shipping.
Why T.E.S IT-SOLUTIONS
Every MCX566A-ECAT unit ships with link verification where test topology is available, EEPROM and vendor data check, full cosmetic inspection, professional anti-static packaging, global B2B shipping from EU stock, and technical consultation at no extra cost.