MikroTik

Hi everyone,

I tried to find answers around, in this forum too and somewhere else.
The question is simple. I would like to buy the Mikrotik hAP ax3 to connect the 2.5g ether1 port to the fiber to copper media converter of my internet service provider.
The media converter is not poe. My question is: sending power to a non poe device will blown the ethernet port of the media converter?
I know that I can disable the poe out function, but as I know it is a software setting and there is no way to disable it phisically (like jumpers or something similar) and
what if, for some reason, it gets activated for any reason like during reboot while software has no control over hardware?

Maybe this question may sound stupid or paranoic.

Thank you very much in advance

It Is not paranoic, It Is a more than legitimate doubt when passive PoE Is involved.
In theory Mikrotik has a primitive form of check (resistance) before providing voltage, but It Is bypassed using "forced on" settings.
To be on the safe side - but the specific device needs to be tested anyway - one could insert on the cable near the media converter a PoE splitter.
Again in theory a splitter should work as an insulator for the PoE voltage, you will need a gigabit splitter.

Thank you for answering to my question.

Last night I had a look to a webpage where is explained how wiring of PoE is designed.
I noticed tha power is injected using the center tap of ethernet transformers and due to the differential nature of ethernet signal the dc on the pair is "ignoired"
and arrives to the center tap of the transformer of the powered device.
In theory, if the receifing device is not internaly wiring its center taps nothing will happen, just like an open circuit.
But in the webpage these type of internal wiring are considered not passive, so I'm still thinking about how Mikrotik implements his passive type of PoE.
In that webpage the only passive type is showing a 10/100 link where two pairs are separated phisically from the data link pairs
Maybe Mikrotik is conssidering passive= without negotiation?

Thank you and sorry for my english

here the link at the webpage
https://www.vorpenergy.com/uncategorize ... -ethernet/

PS. About the spitter I could use one just like a standard rj45 female-female coupler without using power inlet? Eventually the Mikrotik will be powered by a 12v psu using the round jack connector

by default POE is turned OFF and it won't turn on by itself if connected to a device that doesn't ask for power. at least for me it never happened while it's set to auto. if you set it to forced-on, yes it will power anything and probably fry a non-poe device.

you can always use a gigabit poe injector in reverse and plug the eth cable to the injector instead of the router/ont itself. it won't pass DC that way to the client device.

by default POE is turned OFF and it won't turn on by itself if connected to a device that doesn't ask for power. at least for me it never happened while it's set to auto. if you set it to forced-on, yes it will power anything and probably fry a non-poe device.

you can always use a gigabit poe injector in reverse and plug the eth cable to the injector instead of the router/ont itself. it won't pass DC that way to the client device.

Thanks. In reverse means connecting the power out rj45 of the injector to the Eth1 of the Mikrotik and the other port (data only) of the inejctor to the ont.

I'm right?

or vice-versa, doesn't matter, as long nothing is connected to the DC port on the injector.

Yes, most injectors can also act as splitters, but they have to be tested anyway, see:
https://mikrotik.com/product/RBGPOE
viewtopic.php?t=179651

But wait a minute, the ax3 is normally powered at 24V through the jack (and gives out the same 24V or a little less on the poe-out port), if you power it at 12 V there shouldn't be any PoE output, as the minimum is 18 V.

I have multiple AX3-eth1 connected to RB5009 and Hex.
No smoke signals seen yet ...

I have multiple AX3-eth1 connected to RB5009 and Hex.
No smoke signals seen yet ...

Sure, most modern devices are protected about "unwanted" PoE and surely Mikrotik is familiar with Passive Poe, but there are many reports of "random" devices frying because PoE has been applied to one of their ports.

Now, the possibility that accidentally the PoE forced-on setiing is activated by mistake is extremely low, and the ISP media converter is likely to be modern and protected against this, still....

Thank you all for your answers