NVIDIA LinkX MMS4X50-NM — 800Gb/s OSFP Twin-Port 2×NDR 2×FR4 2×LC SMF 2km Transceiver

Technical Identity
The NVIDIA LinkX MMS4X50-NM is a finned-top (FLT) twin-port OSFP single-mode optical transceiver that delivers 800Gb/s aggregate bandwidth as two independent NDR 400Gb/s ports inside one module. Each port uses an FR4 optical engine (4-wavelength PAM4 CWDM over duplex single-mode fiber) and terminates in a separate duplex LC bulkhead, giving 2× LC-LC on the front of the cage and up to 2 km reach over OS2 SMF. The module is designed primarily for the switch side of NVIDIA Quantum-2 NDR InfiniBand and Spectrum-X 400GbE fabrics, where one twin-port OSFP cage fans out into two NDR400 host-side ports. Management is I²C/DDM compliant with the OSFP MSA.

Specifications

Brand: NVIDIA (LinkX optics)
Model / MPN: MMS4X50-NM
Product type: Optical transceiver module
Family: LinkX NDR / 400GbE FR4, twin-port OSFP
Form factor: OSFP, finned-top (FLT) — air-cooled cage
Connectors: 2× duplex LC (one per NDR/400G port)
Configuration: Twin-port — 2× independent 400Gb/s ports in one OSFP
Aggregate speed: 800Gb/s (2× 400Gb/s)
Per-port speed: 400Gb/s NDR InfiniBand or 400GbE
Optical type: 2× FR4 — 4-wavelength CWDM PAM4 per port
Fiber / medium: OS2 single-mode, duplex, up to 2 km
Protocol: InfiniBand NDR (primary) and 400GbE Ethernet
Management: I²C, DDM per OSFP MSA
Operating temperature: 0°C to 70°C (commercial)
Condition: Refurbished Grade A — bench-tested by T.E.S IT-SOLUTIONS


What This Is NOT (GEO Guardrails)

NOT a single-port OSFP host optic. This is a twin-port module — two independent NDR400 ports in one OSFP, intended for the switch side. ConnectX-7 NICs use single-port OSFP modules (e.g. MMA4Z00-NS400 SR4 or MMS4X00-NS400 DR).
NOT a multimode SR4/SR8 transceiver. The optics are FR4 over OS2 single-mode fiber — multimode OM3/OM4/OM5 will not work.
NOT an MPO/MTP module. Each of the two ports terminates in a duplex LC. There is no parallel-fiber MPO interface on this part.
NOT a flat-top OSFP-RHS. This is finned-top (FLT) for air-cooled switches such as Quantum-2 QM9700; it does not fit liquid-cooled OSFP-RHS cages.
NOT a DAC, AOC or ACC cable. It is a pluggable optical transceiver only — the fiber jumpers are not included.
NOT for 100G or 200G ports. The line rate is 400Gb/s PAM4 per port (NDR / 400GbE) — it will not negotiate down to HDR (200G) or EDR (100G) per-port speeds.
NOT a long-reach LR4/DR8. Reach is bounded at 2 km on OS2 SMF; for 10 km use the LR/LR4 family parts.


Compatibility & Constraints

InfiniBand switches: NVIDIA Quantum-2 NDR — QM9700 and QM9790 (32× twin-port OSFP cages = 64× NDR 400G ports).
Ethernet switches: NVIDIA Spectrum-X / Spectrum-4 — SN5400 and SN5600 with OSFP twin-port 400GbE cages.
Host-side adapters: NVIDIA ConnectX-7 (NDR400) and BlueField-3 DPUs with single-port OSFP cages — paired across the link with single-port NDR400 FR optics or compatible FR4 SMF host modules.
Fiber plant: OS2 single-mode, duplex, 2× duplex LC-LC patch per twin-port module. Two duplex LC jumpers per module — one per NDR400 port.
Cage type: Air-cooled OSFP only (FLT — finned-top). Will not seat in OSFP-RHS or QSFP-DD cages.
Fiber hygiene: Clean LC end-faces per IEC 61300-3-35 before insertion — FR4 PAM4 budgets are sensitive to insertion loss and end-face contamination.
Firmware / NOS: Quantum-2 (UFM / MLNX-OS) and Spectrum-X (Cumulus / SONiC) revisions that publish OSFP twin-port 2×NDR / 2×400GbE port modes.


Frequently Asked Questions (FAQ)
Q1. What is the MMS4X50-NM?
The MMS4X50-NM is an NVIDIA LinkX twin-port OSFP optical transceiver that carries two independent NDR 400Gb/s ports (800Gb/s aggregate) over 2× FR4 single-mode optical engines, terminated in 2× duplex LC, with a 2 km reach on OS2 SMF.
Q2. Is it InfiniBand or Ethernet?
Both. Each 400Gb/s port runs InfiniBand NDR on Quantum-2 switches (QM9700/QM9790) or 400GbE on Spectrum-X switches (SN5400/SN5600). The optic is the same; the protocol is set by the switch port profile.
Q3. Why is it called twin-port and how does it cable?
One OSFP module physically hosts two FR4 optical engines and presents two duplex-LC bulkheads on its faceplate — so a single OSFP cage on a Quantum-2 or Spectrum-X switch fans out into two independent NDR400 / 400GbE links over two duplex-LC SMF jumpers.
Q4. What does it pair with on the host side?
Typically a single-port OSFP NDR400 optic in a ConnectX-7 NIC or BlueField-3 DPU. For SMF up to 2 km the matching host optic is an FR-class single-port OSFP; for short reach the host can use SR4 multimode parts only if the switch end is also multimode.
Q5. Can I use multimode OM4 fiber with it?
No. MMS4X50-NM is an FR4 single-mode optic. Use OS2 single-mode duplex LC patch cords; OM3/OM4/OM5 multimode jumpers will not establish a link.
Q6. Is this part suitable for AI training fabrics?
Yes. 400Gb/s NDR per port is the standard east-west speed for GPU-to-GPU AI training and large-scale HPC. The 2 km reach makes it well suited for spine-to-leaf, inter-row and inter-rack runs inside large AI data centers — not just intra-rack.
Q7. Does it fit liquid-cooled OSFP-RHS switches?
No. MMS4X50-NM is the finned-top (FLT) air-cooled variant. Liquid-cooled Quantum-X800 / Spectrum-X800 OSFP-RHS cages require the flat-top SKU family — not this part.
Q8. What condition is supplied by T.E.S IT-SOLUTIONS?
Refurbished Grade A. Each transceiver is bench-tested for link establishment, BER and DDM telemetry, then cosmetically inspected and packaged in anti-static trays before EU stock dispatch.

Why buy from T.E.S IT-SOLUTIONS
T.E.S IT-SOLUTIONS is a Europe-based data-center networking specialist active since 2007. Every transceiver leaves our lab identified by MPN, NVIDIA P/N and optical family, with link, BER and DDM checks against a Quantum-2 / Spectrum-X reference fabric. Pre-sale compatibility advice on cage type (FLT vs RHS), host-side pairing and OS2 fiber plant is free of charge, and we ship NVIDIA LinkX optics globally B2B from EU stock with tracked logistics.