What happens if someone connects a PoE supplier device in my network (In a single switch port)? Does it mean all my network will offer PoE?

Is it possible to detect a PoE supplier in you network?

2 Answers 2


You will not have PoE over your network in that case, the switch does not "redistribute" power to the other ports. If you want PoE, you need either:

  • One PoE injector for each device that require PoE (the injector is plugged between the switch and the device)
  • A switch that does PoE, in that case, every device connected to this switch will be able to have PoE (or not, you can configure it)

If your switch support PoE this means it is able to power devices, but you might have to configure it, and in that case, there is no need for an additional injector.


Short answer is no.

The piece of hardware you are referring to is called a PoE injector. It is designed to sit between your network and a the device needing power to inject power for that one device.

Non PoE switches do not have the circuitry to pass this electrical current to all ports. So reversing a PoE injector and attempting what you are surmising would probably result in a dead switch.

  • What if I have a switch supporting PoE but currently disabled? Can I somehow block it and identify the port which is port injection is happening?
    – user17165
    Aug 11, 2015 at 13:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.