Standards of PoE

Power over Ethernet (PoE) provides power through the Ethernet

PoE power supply standards include IEEE 802.3bt, IEEE 802.3at, and IEEE 802.3af. Its technical specifications vary depending on the PoE power supply standard.

APs are classified as follows by the supported PoE power supply standard:
–802.3bt AP: is also called UPoEAP, and supports IEEE 802.3bt and IEEE 802.3at
–802.3at AP: supports IEEE 802.3at and IEEE 802.3af
–802.3af AP: supports only IEEE 802.3af.

Hi,

PoE is an abbreviation from Power over Ethernet. This technology allows remote power supply of the device via UTP cable.


First, the devices must support PoE. There are many terminal devices that can be powered via a UTP cable. These are devices: POS machines, cameras, data collectors, VoIP phones, wireless access points (APs), etc.


There is a special standard for PoE, it is IEEE 802.3. The standard was developed when it was realized that the two pairs in the UTP cable were unused. Those two pairs could be used for power. Cat 5 UTP cables or higher category cables are used for PoE technology. PoE uses a 48 V power supply.

A PoE system is composed of two segments:

• 
  PSE (Power Sourcing Equipment) - A device that allows remote
  powering of other devices that support PoE technology, and

  
  

• 
  PD (Powered Device) - A device that can be powered via PoE
  technology.

There are two modes of PSE:

• 
  Mid-span PSE. This is an extra device for the remote power supply.
  It is not part of some device. We can use mid-span PSE between
  switches, routers and PDs (figure 1, left side), and

  
  

• 
  End-span PSE. This is a part of some devices (figure 1, right side).
  This type of mode is used for Huawei ONUs.

There are 4 standards.

For more information you can see these links:

https://forum.huawei.com/enterprise/en/utp-cables-4-poe/thread/779695-100181

https://www.black-box.de/en-de/page/23894/Resources/Technical-Resources/Black-Box-Explains/lan/PoE-in-Networking