Power Over Ethernet (PoE)


Power Over Ethernet (PoE) is a network technology with which electric power is carried over the cable that carries data. With this technology, Ethernet cables supply power to the devices over data line. In other words, it is the technology that provide power to the network equipments over CAT5, CAT6 etc. Cables. Here is also wiki definition.


Here, let’s give an example. If you have a camera, you should connect it with two connection. One is network connection and the other is power connection. But with Power Over Ethernet (PoE) technology, you do not need to have two connection. The existing data connection can provide power also.




We should talk about two important device types according to PoE. These device types are:

  • PSE (Power Source Equipment)
  • PD (Powered Devices)


PSE (Power Source Equipment) are the devices that transmit power. Switches, routers can be examples to such devices.


PD (Powered Devices) are the devices that need to be powered to work. Voip phones, Access points, camears are these types of devices.


The standard names are IEEE 802.3af and IEEE 802.3at  for PoE. IEEE 802.3af is the standard of PoE and IEEE 802.3at is the standard of PoE+. PoE+ is the enhanced version of PoE and provide twice as much power as PoE.


PoE+ PSEs can supply bot PoE and PoE PDs, but PoE PSEs supply only its PDs, PoE PDs. Because a PoE PDs need more power that a PoE PSE provide.



Advantages of PoE

Theare are several advantages of using Power over Ethernet (PoE). These advantages are given below:

  • Reduced Costs : There is no need for extra electical powers
  • Flexible: Devices can be located anywhere easily
  • Safety : Better for power overload, underpowering etc.
  • Reliable : Power comes from a central point
  • Scalable : Simple and effective network installation and distribution



PoE Devices

There are several devices that is used for PoE (Power over Ethernet). So, what are these devices used with PoE? These are :


  • Power Over Ethernet Switch (PoE Switch)
  • Power Over Ethernet Hub (PoE Hub)
  • Power Over Ethernet Splitter (PoE Splitter)
  • Power Over Ethernet Injector (PoE Injector)
  • Power Over Ethernet Extender (PoE Extender)




PoE Switch is the switches that is PoE capable. These switches support PoE on their each port.

PoE Hub is the device that is consist of different ports as PoE injectors. With these PoE injectors, power can be supplied to different PDs.

PoE Splitter is the devices that supplies power to low  power devices like cameras, Access points etc. This devices convert voltages to a lower value that the devices can use.


PoE Injector is used to send power from PoE uncompatible switches to PoE PDs. It is used by old equipments that is not PoE capable.


PoE Extender is used to extend the distance that is determined as 100m. With this equipment, power supply can be doen through more than this distance.



How to Upgrade Existing Network to PoE?

New network equipments are generally PoE compatibl. But sometimes in the networkss there can be old equipments, for example there can be switches that do not support Power Over Ethernet (PoE). To overcome this issue and to add PoE capability to your network, an extra device must be used. The name of this device is “midspan” or “PoE injector”. With these devices, non-PoE links is upgraded to PoE links.


We can also upgrade cameras, Access points to Power Over Ethernet (PoE) with PoE splitter. PoE splitter is patched to the network connection of the camera and gives a reduced voltage to cameras.


In today’s World, Power Over Ethernet (PoE) is used with many network devices. You can see any network device in your enterprise network or in any datacenter, almost all devices use this excellent technology to reduce costs, to have an effective and scalable network connections.

Lesson tags: PoE
Back to: CCNA 200-301 v1.1 > Network Fundamentals

Leave a Reply

Your email address will not be published. Required fields are marked *

CCNA 200-301 v1.1