All About QSA Adapter

Version 2

    This post introduces the QSFP-to-SFP Adapter (QSA) and the QSA28 Ethernet adapters.


    Problem: You have a 4-channel QSFP port on a switch or network adapter but you’ve got a single-channel subsystem that uses SFP and you want to connect older equipment, storage or a 10G device. Or you have a new shiny 25Gb/s-based Spectrum switch or ConnectX-4 or -5 network adapters and you want to connect to slower 10Gb/s equipment. How do you connect the different port types and speeds together?


    Answer: Get the Mellanox QSA Adapter. - now supporting 25Gb/s! Sometimes, the simplest things can solve big problems and frustrations. The QSA is one such device and costs less than a dinner for one.





    The QSA adapter is a Mellanox designed and patented, mechanical adapter that fits neatly inside a QSFP port and enables plugging in a smaller, single-channel SFP device into a QSFP 4-channel port.  Only the one-channel gets passed through even though the mechanical port is 4-channels.  The QSA contains a configuration EPROM to tell the host the transceiver information. The QSA is passive and consumes no power. In addition, it does not induce and signal latency delays.


    Not everything in the world runs or needs to run at 25Gb/s so the QSA is a neat way to link slower 10G sub-systems to new high-speed Spectrum switches and ConnectX-5 network adapter and later upgrade the slower equipment to 25Gb/s.



    QSA Types

    There are two types of QSA adapters:

    • QSA+ (40 > 10G) adapter
    • QSA28 (100 > 25G) adapter


    QSA+ 40>10G Adapter

    P/N: MAM1Q00A-QSA - Blue tab

    Supports also 1G


    QSA28 100>25G Adapter

    P/N: MAM1Q00A-QSA28 - Black tab

    Supports also 10G, 1G




    Supported Cables

    QSA accepts a huge range of 10G and 25G cables and transceiver types:

    • CR DAC copper SFP (3-7m)
    • SR SFP multi-mode transceiver (100m)
    • SFP multi-mode AOCs (100m)
    • LR SFP single-mode transceiver (10km)
    • SX 1G SFP+ multi-mode transceiver (500m)
    • Base-T 1G SFP converter that uses CAT-5 copper UTP cables (100m)





    Refer to HowTo use Mellanox QSA.