Switching

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Ask questions and share experiences about EX and QFX portfolios and all switching solutions across your data center, campus, and branch locations.
  • 1.  Why can I not mix power supplies in the EX4300(-32F)? I want DC and AC!!!

    Posted 17 days ago

    The subject says it all: Why can I not mix power supplies in the EX4300(-32F)? I want DC and AC!!!

    The hardware guide says one can only use AC or DC, but from an electrical (and my) point of view, the secondary side (the one facing the switch) should be identical regardless of the input power type. What is the problem here, really? Has anyone run the AC-DC combo in the EX4300 or similar switch? I'd be wiling to try myself, but cannot recommend it to a customer without more info.



  • 2.  RE: Why can I not mix power supplies in the EX4300(-32F)? I want DC and AC!!!

    Posted 16 days ago

    Well, here it is clearly stated that you should avoid mixing AC and DC power in the same chassis - 

    https://www.juniper.net/documentation/us/en/hardware/ex4300/topics/topic-map/ex4300-power-system.html

    I believe there are very specific reasons why AC+DC setup is not recommended for any other equipment, not only this model.



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    FARID AKHUNDOV
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  • 3.  RE: Why can I not mix power supplies in the EX4300(-32F)? I want DC and AC!!!

    Posted 16 days ago

    Yes, it is clearly documented, so no issues there, but I guess I'm a bit frustrated since I cannot see an electrical problem mixing the two. Grounding and cabling could be one issue, but hardly on modern hardware. There are other switch brands that allow this in certain models but not in other (Nokia SAS-S does not, SAS-Mxp does).

    Electrically, an AC feed to a switching power supply (which all are today in this product segment) is rectified to DC the first thing that happens in the PSU, so from there on, it is a DC PSU anyway, just with a higher voltage than a -48 VDC PSU.

    As I said, perhaps more frustrated than expecting Juniper to change their policy... If anyone with real hard core electronics knowledge can shed some light, I'm all ears!




  • 4.  RE: Why can I not mix power supplies in the EX4300(-32F)? I want DC and AC!!!

    Posted 16 days ago

    Surely, from electronics point of view nearly all the circuitry inside the switch is fed from DC. I think other vendors also have similar policies.



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    FARID AKHUNDOV
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