NVIDIA Mellanox® MCX556N-ECAT — ConnectX-5 EDR 100Gb/s Dual-Port QSFP28 Adapter, PCIe 4.0 x16
Technical Identity
The NVIDIA Mellanox® MCX556N-ECAT is a ConnectX-5 dual-port QSFP28 host channel adapter rated at EDR InfiniBand 100Gb/s per port, on a PCIe 4.0 x16 host interface, low-profile (short) form factor, CAPI-capable. This unit is supplied under the generic NVIDIA Mellanox part number: no OEM part number is present on this card. It is the same hardware family as the IBM-FRU-marked variant that IBM catalogues as 00WT176 (PCIe4 x16, 2-Port EDR 100Gb InfiniBand ConnectX-5 CAPI Adapter, low profile), listed separately by T.E.S IT-SOLUTIONS. Condition: Refurbished Grade A.
Specifications
Brand: NVIDIA Mellanox
Model / MPN: MCX556N-ECAT
OEM part number: none on this unit (generic NVIDIA Mellanox P/N)
Related OEM variant: IBM FRU 00WT176 — same hardware family, listed separately
NVIDIA ordering P/N: not verified for this OPN — verify against the unit label
Product type: InfiniBand host channel adapter (HCA)
Product family: NVIDIA ConnectX-5
Ports: 2 × QSFP28
Per-port speed: EDR InfiniBand 100Gb/s
Lane structure: 4 × 25G-NRZ per QSFP28 port
Host interface: PCIe 4.0 x16
CAPI: CAPI-capable per the OEM description of this part
Bracket: Low-profile (short)
Condition: Refurbished Grade A
Engineering Context
Host bus headroom: PCIe 4.0 x16 supplies roughly 256Gb/s of raw bus bandwidth including overhead, which is what lets both 100Gb/s QSFP28 ports run concurrently. PCIe 3.0 x16 caps aggregate throughput at roughly 128Gb/s.
ConnectX-5 offload set: MPI Tag Matching and MPI All-to-All collective offloads, adaptive routing on reliable transport, burst-buffer offloads for background checkpointing.
RDMA and storage: IBTA RDMA over InfiniBand, NVMe-over-Fabrics target offload, SR-IOV, PeerDirect / GPUDirect. Feature availability depends on firmware, driver, OS and platform configuration.
Use Cases
EDR 100Gb/s InfiniBand compute-node connectivity in HPC and AI clusters.
Low-profile 1U and 2U chassis where a tall-bracket adapter will not fit.
Buyers who need the generic NVIDIA Mellanox part number rather than an OEM-marked FRU.
RDMA storage fabrics, NVMe-over-Fabrics target nodes, lab and spares inventory.
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 HDR or NDR capable. Maximum per-port rate is 100Gb/s EDR. HDR 200Gb/s needs ConnectX-6 class silicon; NDR 400Gb/s needs ConnectX-7 class silicon.
NOT an IBM-FRU-marked unit. This card carries no OEM part number. If your process requires the IBM 00WT176 marking, order that listing instead.
NOT the retail MCX556A-ECAT, which is documented as PCIe 3.0 x16 with a tall bracket.
NOT a tall-bracket card. Only the low-profile bracket is fitted.
NOT a PTP / SMA timing variant. Hardware PTP with an SMA connector belongs to the verified MCX556A-EDAM variant.
NOT a verified Multi-Host adapter. Multi-Host on this generation is carried by separately identified SKUs such as MCX556M-ECAT-S25.
NOT supplied with QSFP28 transceivers, DAC or AOC cables, tall bracket, or installation accessories.
Compatibility & Hard Constraints
Typical InfiniBand head-end platforms include: NVIDIA Switch-IB 2 and other EDR-class 100Gb/s InfiniBand switches with QSFP28 ports.
Typical host platforms include: servers offering a low-profile PCIe x16 slot, including the POWER-architecture systems for which the OEM variant is listed.
Slot requirement: PCIe 4.0 x16 for full concurrent dual-port line rate.
Cabling: QSFP28 EDR 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.
Protocol note: catalogued as an EDR 100Gb InfiniBand adapter. If Ethernet operation is required, confirm port link type and firmware support with mlxconfig rather than assuming it.
Pre-deployment verification: adapter firmware, driver version, port-mode configuration, chassis bracket clearance and switch firmware must match.
Frequently Asked Questions (FAQ)
Q. What is the NVIDIA Mellanox MCX556N-ECAT?
MCX556N-ECAT is a ConnectX-5 dual-port QSFP28 host channel adapter rated at EDR InfiniBand 100Gb/s per port on a PCIe 4.0 x16 host interface, low-profile form factor, CAPI-capable. This unit is sold under the generic NVIDIA Mellanox part number MCX556N-ECAT.
Q. Does this MCX556N-ECAT carry an OEM part number?
No. This unit carries no OEM part number. The same MCX556N-ECAT hardware is also distributed by IBM under FRU 00WT176, which T.E.S IT-SOLUTIONS lists separately. If your process requires the IBM FRU marking, order the 00WT176 listing instead.
Q. What connector cage does MCX556N-ECAT use?
Two QSFP28 cages, each carrying 4 lanes of 25G-NRZ for 100Gb/s. MCX556N-ECAT will not accept QSFP56, QSFP112, QSFP-DD or OSFP modules. Only QSFP28-class EDR 100Gb/s DAC, AOC or optical modules fit.
Q. Does MCX556N-ECAT support HDR 200Gb/s or NDR 400Gb/s?
No. MCX556N-ECAT is ConnectX-5 silicon 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 does MCX556N-ECAT differ from MCX556A-ECAT?
NVIDIA documents MCX556A-ECAT as a PCIe 3.0 x16 card with a tall bracket. MCX556N-ECAT is documented in its OEM form as PCIe4 x16, CAPI-capable and low profile. Treat slot generation and bracket height as different between the two.
Q. What slot and cabling does MCX556N-ECAT need?
A PCIe 4.0 x16 slot to feed both 100Gb/s QSFP28 ports concurrently; PCIe 3.0 x16 caps aggregate throughput at roughly 128Gb/s. Cabling must be QSFP28 EDR 100Gb/s DAC, AOC or optics, not included.
Q. What condition is supplied by T.E.S IT-SOLUTIONS?
Refurbished Grade A. Each MCX556N-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 MCX556N-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 for HPC and AI fabric design at no extra cost.