Application Overview

MMS4X50-NM 800Gbps Twin-port OSFP 2xFR4, 2x400Gbs Single Mode, 2km

The Twin-port transceiver is a key innovation for expanding the 400G NDR InfiniBand Quantum-2 and 400GbE Spectrum-4 Ethernet (400G IB/EN) switch capabilities. The line rate is 400Gb/s for both 400GbE Ethernet and NDR InfiniBand based on the 100G-PAM4 modulation. The switches use Twin port OSFP cages supporting two transceiver engines in a single OSFP form-factor plug creating 800Gb/s electrical to the switch and 2x400G multiplexed optics using duplex LC optical connectors.
Each LC-based fiber cable can link to another 2xFR4 transceiver transferring 800Gb/s or to two separate 2xFR4s in separate switches at 400Gb/s for a total of three switches linked. Additionally, since the LC fiber cables send 4x100G-PAM4 CWDM4 signals, they can also link to 400G FR4 QSFP-DD transceivers there by enabling bridging 50G-PAM4 Spectrum-3 to 100G-PAM4 Spectrum-4 Ethernet systems.

The primary use case for the MMS4X50-NM transceiver is to link multiple switches together up to 2km reaches.

  • FR4 CWDM4 multiplexing combines 4 different wavelength laser data signals into a single fiber which is filtered back to 4 in the receiving transceiver.

  • Used for long fiber runs and in complex fiber infrastructures to save fiber costs.

  • Linking two transceivers directly together, the LC fibers must be crossed over to align transmit lasers with receive photodetectors.

  • Twin-Port transceivers require ordering two fibers at specific lengths. NVIDIA does not supply these fibers.

  • Fiber splitters cannot be used with CWDM4 transceivers, as the wavelengths are multiplexed together into one fiber.

  • Both fibers should be the approximately same length to avoid inducing different latency delays in the fibers (4.5ns/meter).

The use cases include:

  1. Switch-to-switch at 800Gb/s

    This configuration enables transferring 800Gb/s between two switches using a single transceiver in each switch. The 2xFR4 supports both InfiniBand and Ethernet and can link two InfiniBand Quantum-2 switches or two Ethernet SN5600 switches together using only 4 fibers in total. Additionally, one 800G switch can link two switches at 400G using separate fiber to each 2xFR4 in the switches.


  2. 800G switch-to-two QSFP-DD switches at 400Gb/s

    A 2xFR4 Twin port OSFP transceiver can have each 400G fiber cable sent to two QSFP-DD FR4 transceivers as both operate optically at 100G-PAM4. This enables 8x50G-PAM4 electrical Spectrum-3 Ethernet SN4700 QSFP-DD switches to link to a 64-port Ethernet SN5600 Spectrum-4 Twin port OSFP switch. Additionally, each 400G FR4 could be inserted into two different QSFP-DD switches.
    The 400G FR4 QSFP-DD transceiver employs an 8x50G-PAM4 electrical side and uses an internal “gearbox” IC to translate to 4x100G-PAM4 optical which can link to the 2xFR4 Twin port OSFP..


© Copyright 2023, NVIDIA. Last updated on Nov 6, 2023.