PoE (Power over Ethernet) is a technology with which it is possible to power certain devices with the same Ethernet cable that connects them to the network, saving both money and time. The market currently offers different types of these switches: in addition to PoE, there is PoE+ and PoE++. But what are the differences? And how to choose? 

What is PoE and the PoE switch? 

What is PoE? PoE technology was defined by the IEEE 802.3af standard in 2003. According to this standard, PoE allows a powered device (e.g. a VoIP telephone) to receive PoE power of up to 12.95 W, using only two of the four available wire pairs in Ethernet cabling. 

The PoE switch, functioning as a kind of PSE (Power Sourcing Equipment), can supply power to devices via Ethernet cables to realise network connectivity. Typically, an 802.3af switch supports a maximum power consumption of up to 15.4 W per PoE port, with a voltage range of 44 V to 57 V. And the voltage range of devices, connected to the PoE switch, is from 37V to 57V. 

What is PoE+ and the PoE+ switch? 

PoE+ technology (IEEE 802.3at standard) is an update of PoE technology, released in 2009. Powered devices on the market tend to require more wattage, such as wireless access points that require PoE wattage above 12.95W to function normally. PoE+ technology was designed precisely to solve this problem: supporting high power consumption. 

Similar to a PoE network switch, the PoE plus switch also provides power in two pairs, but provides an additional power class capable of providing power up to 25.5 W for a device with a voltage range of 42.5 V to 57 V. The maximum power delivered by each port of a PoE+ switch is 30 W, along with a voltage range of 50 V to 57 V. 

What is PoE+ and the PoE+ switch? 

PoE++ is a further upgrade of the technology to increase power. It can be classified into two types: Type 3 and Type 4. Type 3 allows two or all four wire pairs in a copper cable to supply power to a device up to 51 W. Type 4 allows the device to power up to 71 W over four wire pairs in an Ethernet cable.  

As an upgrade of the PoE switch and PoE+ switch, the PoE+ switch can provide up to 60 W on each PoE port with Type 3 and up to 100 W with Type 4. 

PoE switches vs PoE + vs PoE ++: which one to choose? 

Based on the information provided above, the following is a reference table summarising the detailed specifications between PoE vs PoE + vs PoE ++, which may be useful when choosing which switch to use 

Of course, these figures are indicative, as PoE series switches often exceed the total power capacity of a multi-port switch. This is because many devices will use less than the maximum power. For example, if you have a switch with all PoE ++ ports of type 4, this does not mean that they will all be used at the maximum 24 × 7 load. Therefore, you must calculate the power requirements for all powered devices that you plan to connect to the switch, and select the corresponding patch cords for your PoE design. 

Clearly, the main differences between PoE, PoE + and PoE ++ switches lie in their mode of operation and power supply, which are reflected in their applications. An 802.3af switch is usually used to support devices requiring a power supply of less than 15.4 W, such as VoIP telephones, sensors, meters, wireless access points with two antennas and simple static surveillance cameras, which cannot pan, tilt or zoom. As for the PoE+ switch, it supports devices such as more complex surveillance cameras, which pan, tilt or zoom, as well as wireless access points with six antennas and IP video telephones. With a higher power wattage, the Type 3 PoE ++ switch can support devices such as video conferencing system components and building management devices. And the Type 4 PoE++ switch can support devices such as laptops and TVs. 

Assuming that your data centre only requires low standard power levels, you can refer to PoE switches. However, if you wish to build a more robust, high-performance network with different devices, and, at the same time, do not want to worry about considering port limits, your choice should be PoE+ or PoE+ switches. When you start thinking about infrastructures with more sophisticated requirements or plan upgrades, opting for PoE + or PoE ++ technologies might be the best alternative. However, not everyone needs a complete upgrade. If your current PoE solution is adequate and meets your needs, it may make sense to maintain your existing PoE network design.