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DAC cable interoperability QSFP28

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  • 1.  DAC cable interoperability QSFP28

    Posted Jul 27, 2022 01:43 AM

    Which DAC cable will work between a CX 10000 QSFP28 100Gbs ports and the

    HPE InfiniBand EDR/Ethernet 100Gb 2-port 841QSFP28 Adapter part#  872726-B21
    (Short, ~2 - 3 meters)



  • 2.  RE: DAC cable interoperability QSFP28

    MVP GURU
    Posted Jul 27, 2022 09:12 AM
    Hi Steinar Grande,

    That's interesting.

    The very first fact is that your HPE InfiniBand EDR/Ethernet 100Gb 2-port 841QSFP28 Adapter isn't simply an Ethernet-only adapter but it features dual functions (see also the HPE EDR InfiniBand Adapters Data sheet): InfiniBand or Ethernet (per port) and that maybe explains why it can't be found on any HPE Compute transceiver and cable hardware matrix (Product Availability Matrix) document published so far (including the latest Revision 21 of June 2022 I linked), matrix where many different Ethernet-only based products can be found instead:

    SFP/SFP+ Direct Attach Cables for HPE ProLiant Network Adapters
    SFP/SFP+ Transceivers for HPE ProLiant Networking Adapters
    SFP28 Direct Attach Cables for HPE ProLiant Network Adapters
    SFP28 Active Optical Cables for HPE ProLiant Network Adapters
    SFP28 Transceivers for HPE ProLiant Network Adapters
    QSFP28 Direct Attach Cables for HPE ProLiant Network Adapters
    QSFP28 Active Optical Cables for HPE ProLiant Network Adapters
    QSFP28/QSFP+ Transceivers for HPE ProLiant Network Adapters
    Splitter Cables (DAC/AOC) for HPE ProLiant Networking Adapters
    Fiber Optic Cables for HPE ProLiant Networking
    Aruba Systems and Products supported with HPE ProLiant Networking Adapters
    HPE FlexFabric/HPE FlexNetwork Cable Support List for HPE ProLiant Network Adapters

    The second fact is that, looking at the MCX5xx chip (Mellanox ConnectX-5 network processor) of your InfiniBand EDR/Ethernet 100Gb 2-ports adapter, it can be easily recognized that an adapter driven by a similar Chip - the MCX515A (not dual function so not InfiniBand so just Ethernet) - could be the HPE 100GbE 2P QFP28 MCX516A-CCHT Adapter (SKU P21927-B21) and that particular Ethernet adapter supports all those DACs (HPE and Aruba):

    845406-B21 HPE 100Gb QSFP28 to QSFP28 3m DAC
    845408-B21 HPE 100Gb QSFP28 to QSFP28 5m DAC
    R0Z25A Aruba 100G QSFP28 to QSFP28 1m DAC Cable
    JL307A Aruba 100G QSFP28-QSFP28 3m DAC Cable
    R0Z26A Aruba 100G QSFP28 to QSFP28 5m DAC Cable

    A note says that Aruba DACs are supported with Aruba ToR infrastructure only (and I read that note as it says "with Aruba CX 83xx and Aruba CX 10000 series")...indeed looking at the Aruba AOS-S and AOS-CX Transceiver Guide Edition 11 (December 2021) supported passive 100G DACs by the Aruba CX 10000 are respectively:

    R0Z25A Aruba 100G QSFP28 to QSFP28 1m Direct Attach Copper Cable
    JL307A 100G QSFP28 to QSFP28 3m Direct Attach Copper Cable
    R0Z26A 100G QSFP28 to QSFP28 5m Direct Attach Copper Cable

    And there is the statement that the Aruba CX 10000 48Y6C model (R8S96A displayed by CLI) supports exactly JL307A and R0Z25A/R0Z26A (these two since AOS-CX 10.09.0010).

    Long story short to say only that I suspect that using either JL307A or R0Z25A/R0Z26A would work with your Aruba CX 10000...at least looking at the switch side.

    On the other hand, specifically looking at supported options of your adapter it looks like that supported passive DACs are only:

    834973-B21 HPE 0.5m InfiniBand EDR QSFP Copper Cable
    834973-B22 HPE 1m InfiniBand EDR QSFP Copper Cable
    834973-B23 HPE 1.5m InfiniBand EDR QSFP Copper Cable
    834973-B24 HPE 2m InfiniBand EDR QSFP Copper Cable
    834973-B25 HPE 3m InfiniBand EDR QSFP Copper Cable

    Again if there could be an issue, if any, it could be eventually fall on the Adapter side especially if your approach requires to use Aruba supported DACs on the Aruba CX 10000 (which is a good thing to do) as the very first and essential requirement...


    Original Message


  • 3.  RE: DAC cable interoperability QSFP28

    Posted Jul 27, 2022 09:29 AM
    Hi, there

    Thank you so much, I will investigate this carefully

    Thank you for pointing out another card option,

    I do not need infiniBand,

     

    It stands between dac cables and a number of transceivers

    (845972-B21

    HPE 100Gb QSFP28 Bidirectional XCVR)

    Original Message


  • 4.  RE: DAC cable interoperability QSFP28

    MVP GURU
    Posted Jul 27, 2022 10:34 AM
    If you are still free to change the Network Adapter adopting one listed on the HPE Compute transceiver and cable hardware matrix it would be far better since there is at least one 100Gbps dual ports adapter which is "compatible" with Aruba CX 83xx and Aruba CX 10000 using DACs and/or - to avoid compatibility issues or unavoidable scenarios where DACs incompatibility can't be fixed - using supported QSFP28 Transceivers (each side needs its supported QSFP28 Transceiver option so it's little bit easier - even if it is less cheaper than using DACs - to fulfill imposed requirements on each end, HPE and Aruba).
    Original Message