What is PoE? PoE technology was defined by the IEEE 802.3af standard in 2003. Under this standard, the PoE allows a PD (powered device) like VoIP phones to receive up to 12.95W PoE wattage, utilizing just two out of the available four twisted pairs in Ethernet cabling.
Then what is a PoE switch? PoE switch refers to an application of PoE technology. Functioning as a kind of PSE (power sourcing equipment), a PoE switch can supply power to PDs via Ethernet cables to realize network connectivity. Generally, an 802.3af switch supports max power consumption up to 15.4W per PoE port with a voltage range between 44V and 57V. And the voltage range of PDs, connected with the PoE switch, is from 37V to 57V.
What Is PoE+ and PoE+ Switch?
PoE+ technology (IEEE 802.3at standard) is an upgrade of PoE technology, which was published in 2009. PDs in the market tend to require more wattages, like wireless access points that require PoE wattage more than 12.95W to work normally. To solve that, here comes the PoE plus technology, which can support high power consumption.
Similar to a PoE network switch, the PoE plus switch also supplies power over two pairs, but it adds an additional power class that is able to deliver power up to 25.5W for a PD with a voltage range from 42.5V to 57V. The max power delivered by each port of a PoE+ switch is 30W, along with a voltage range from 50V to 57V.
What Is PoE++ and PoE++ Switch?
In the pursuit of adding more power to broader device applications, the IEEE 802.3 standard once again is required to upgrade its PoE+ technology to PoE++ (IEEE 802.3bt standard) in 2018. PoE++ can be classified into two types: Type 3 and Type 4. Type 3 enables two or all four twisted pairs in a copper cable to deliver power at a PD up to 51W. Type 4 is up to 71W at a PD over four twisted pairs in an Ethernet cable. By the way, Cisco’s proprietary technology UPoE (universal Power over Ethernet) works similarly to the PoE++ Type 3, which extends the IEEE PoE+ standard to double the power to a PD to 51 watts. In some cases, UPoE is also called as PoE++.
As an upgrade to Power over Ethernet switch and PoE plus switch, PoE++ switch can deliver up to 60W on each PoE port under the Type 3 and up to 100W under the Type 4.