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I've got a PD (Powered Device : Ubiquity AirCube ISP access point) and a PSE (Power Sourcing Equipment : TP-Link TL-SG1005P switch).

My understanding is that there are two ways of supplying power : A and B. The PSE (switch) in this case supports A. It is also my understanding that for a PD (access point) to be compliant, it needs to support both A and B. So in other words, the PSE controls which one to use.

At present, all of TP-Link’s PoE switches are standard PSE and designed based on the Alternative A and the line pair 1/2 is passive pole while the line pair 3/6 is the positive pole.

https://www.tp-link.com/no/support/faq/1003/

The PSE, not the PD, decides whether power mode A or B shall be used. PDs that implement only mode A or mode B are disallowed by the standard.

https://en.wikipedia.org/wiki/Power_over_Ethernet

I'm connecting the PD directly into the PSE using a CAT5e cable. The cable goes from port 1 on the PSE to the 24v PoE IN port on the PD.

The PD does not indicate power, so either I'm doing something wrong or the equipment is not compatible.

Have I missed anything with regards to how PoE devices work?

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sbrattla
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    There is multiple standards of PoE IEEE 802.3af , at , bt, and also non standards. The standards are AFAIK 48V. Can you update with exact model number? "PoE Out Controllable 24V PoE Out (4, 5+, 7, 8-) on WAN Port" – NiKiZe Jan 09 '22 at 14:52
  • @NiKiZe added links for the products in question. – sbrattla Jan 09 '22 at 14:56

1 Answers1

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from port 1 on the PSE to the 24v PoE IN port on the PD

There's the problem. Apparently, the Aircube ISP uses a proprietary "PoE" variant as indicated by the 24V designation. IEEE PoE is 54/48V generally.

Ubiquiti is notorious for using various "PoE" variants. If they don't say 802.3af, 802.3at, 802.3bt anywhere, it's likely not compatible with any other vendor's device.

The PoE from the switch isn't of any use here, sadly. You'll need to put a compatible Ubiquiti 24V injector between switch and the Aircube.

Zac67
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    I naively assumed that PoE advertised devices from known brands would adhere to standards, but wrongly assumed so. I'll power the devices over USB instead then; the required additional equipment from Ubiquity is much more expensive than USB chargers. Thanks! – sbrattla Jan 09 '22 at 16:11