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40Gb DAC in 5940 QSFP even ports

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  • 1.  40Gb DAC in 5940 QSFP even ports

    Posted Mar 01, 2022 02:39 PM
    We have a 5940 48SFP+ 6QSFP28 switch. We'd like to use 40Gb DAC cables to connect 6 hosts at 40Gb to the switch using the 6 QSFP28 ports.  

    We're running into an odd situation. We can connect fine to the odd number (top) ports (49,51,53) but not to the bottom ports (50,52,54). When we move the cables from the bottom ports to the top ports, they link fine. The transceivers are not recognized at all in the bottom ports. 

    Has anyone seen this issue?

    This is our only only Comware deployment so it's possible I might be missing some sort of config to enable all 6 ports?

    Richard Angeletti

  • 2.  RE: 40Gb DAC in 5940 QSFP even ports

    Posted Mar 02, 2022 07:06 AM
    Hi Richard, what a display interface brief CLI command reports? if QSFP+ bottom ports 1/0/50, 1/0/52 and 1/0/54 were left at their default state (neither previously used for IRF nor for 4x10G splitting through Hydra cables <- I'm supposing) it's pretty much strange they behave differently than top QSFP+ ports 1/0/49, 1/0/51 and 1/0/53.

    Davide Poletto

  • 3.  RE: 40Gb DAC in 5940 QSFP even ports
    Best Answer

    Posted Mar 02, 2022 10:34 AM
    Apologies. My post was stuck in moderation and I couldn't update it yesterday.

    Work was at a remote site and said site has other switches with QSFP where the port orientation alternate so the pull handles on the QSFPs are as far apart as possible for stacked ports (ports directly abiove or below each other), it appears that is not the orientation of the QSFP on the 5940. All 6 ports are oriented in the same manner. Once the on site person properly inserted the DAC in the QSFP it worked fine.

    Richard Angeletti