Jumper usage
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If the destination device does not support PoE powering, the power passthrough can be disabled manually by removing both jumpers on the “PoE out” side.
What about jumper on “PoE in” side ? Can’t find any information on those
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Powering
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The device require power to the Ethernet port:
• Ethernet port accepts passive PoE or 802.3af/at DC 24 - 57 V⎓
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Jumper usage
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This will only work if “PoE in” is served by passive PoE source, as 802.3af/at switches will not be able to power the GPeR itself.
Pretty confusing… can be powered or not by 802.3af/at ?
Test:
802.3af switch → GPeR jumper on → non poe device (laptop) : does not work, no link on GPeR, no link on laptop
802.3af switch → GPeR jumper off → non poe device (laptop) : does not work, no link on GPeR, no link on laptop
802.3af switch → GPeR jumper on → poe device (Access point) : it is working
My understanding is that GPeR can not negociate with 802.3af/at switch or injector to ask the switch to send power, so it is not compatible with 802.3af/at and should not be advertised as such.
If by luck, device connected to the PoE-out side is 802.3af/at, that remote device will negotiate with the 802.3at/af compliant switch or injector. GPeR will be passive passthrough until the PoE switch or injector apply power. Then the GPeR will sink current on the 802.3af/at activated link and become an ethernet switch. I have some doubt on long line or with multiple GPeR in series if that 802.3af/at negotiation can even work.
Can someone from Mikrotik can confirm and comment ?
Correct me if I am wrong here: It looks as if the designers of this device skimped and did not put proper IEEE 802.3af/at circuitry into this extender. Which would mean that if the device connected to the "input" port supplies IEEE power, the extender will not work unless the device on the "output" port negotiates power (after which the extender pirates some for itself). But if the device on the "input" port provides non-IEEE, passive, "always on" PoE, the extender will always work (and pass power through to the "output" port unless some jumpers are removed).
This is awkward. It makes the extender useless for inter-building links where you have AC-powered devices at both ends, UNLESS you happen to have a switch at one end with passive PoE (rare; some old Ubiquiti ones do) or add a WISP-style passive PoE injector and REMEMBER TO PULL THE JUMPERS to avoid possibly producing smoke in the device on the "output" port. And all of this is VERY poorly documented. For example, the documentation says to pull TWO of the jumpers if you do not want passive power to pass through, when in fact you need to pull ALL FOUR or risk shorting out your passive PoE injector or damaging the device on the "output" port. (There is no actual explanation of what the jumpers connect or disconnect.) Is Mikrotik planning to make a true IEEE-capable extender that will work under all conditions without a kludge? To at least fix the documentation of the existing one?
Yours could be a good question, but if you actually want an answer to It maybe you should ask it to Mikrotik (support, as opposed to here on the user forum)?
I have tried to contact them; did not get through.
We've done a bit more investigation on the device, though, and it appears that (despite what the documentation says) each of the 4 jumpers on the GPeR makes or breaks the connection on one of the four pairs of transformer center taps. The two on the "input" side seem to connect to the (4,5) and (7,8) center taps while the two on the output side seem to be (1,2) and (3,6). So, you do indeed need to remove all four to make sure that PoE power does not pass through. It would be good if the documentation said this, because it would avoid damage to connected devices.
It sounds accurate, as many (most?) PoE extenders may make a "Mode change", usually from Mode A to Mode B.
I never understood the reasons why, sometimes Mode B Is called "midspan" and Mode A Is called "endspan".
Since Mikrotik devices usually use Mode B, It seems natural that the (4,5) and (7,8) are on the input side (the one connected to the Mikrotik PSE and the (1,2) and (3,6) are on the output side.
I wonder if there Is actually a Mode conversion in the GPER or not.