PoE Quick Guide - an introduction to the technology
Power over Ethernet (PoE) is a common part of three networking standards - IEEE 802.3af, IEEE 802.3at and the latest for the moment, IEEE 802.3bt. As the name suggests, this technology allows us to provide power to network devices using existing infrastructure. Each of the above-mentioned classes of PoE has its own specification differing in the type of cable, but also in the maximum current or most important, the maximum power delivered by the power supply device.
PoE standards
Subsequent standards for this technology were developed as more and more "current-consuming" devices appeared, and switches capable of powering them.
| PoE standard | Other names for the standard | Output power | Year of creation | Power available |
| IEEE 802.3af | PoE | 15,40 W | 2003 | 12,95 W |
| IEEE 802.3at | PoE+ | 30 W | 2009 | 25,50 W |
| IEEE 802.3bt Type 3 | PoE++ , UPoE, Ultra PoE, 4PPoE | 60 W | 2018 | 51 W |
| IEEE 802.3bt Type 4 | PoE++ , UPoE, Ultra PoE, 4PPoE | 100 W | 2018 | 71 W |
Application
Depending on our existing network infrastructure, we can either power devices directly from the network switch, or through a dedicated device that adds power to the data link. The first way requires a switch that has sufficient power and is designed to power devices, such switches can be all Allied Telesis switches whose models end with the letters "PS", such as AT-GS950/28PS or models ending with "P" or "FP" in the case of EnGenius devices, one of our manufacturers that work best with devices using this type of power supply.
In a situation where the switches we already have in the network do not have Power over Ethernet functionality, it is necessary to use a so-called PoE injector, a device that will enrich the network cable with power, such as Microchip models.
In addition, for increased reliability and safety, protection of the system, we recommend the use of Line Interactive UPS class with a power of 1000VA and above in a free-standing or rack 1U enclosure, which are connected to the switch and POE injector - they will allow you to temporarily sustain the operation of the network and safely shut it down, without losing data or burning the connected devices.
More advanced switches (such as the ECS2528FP models from EnGenius) are equipped with a set of features designed for surveillance and surveillance work, such as:
- PoE Extended mode
allowing to extend the maximum range of the camera installation up to 250 meters - PD lifeguard
monitors the status of the cameras and automatically restarts them when any of them is turned off - continuous PoE power supply function
forces the switch to continuously supply power to connected cameras or VOIP phones during a reboot after a switch software update