PoE vs PoE+ vs PoE++

Hello everyone,

PoE (Power over Ethernet) refers to supplying power through an Ethernet network, also known as a local area network-based power supply system PoL (Power over LAN) or Active Ethernet. The PoE system supports three standards: 802.3af (PoE), 802.3at (PoE+), and 802.3bt (PoE++).

What is a PoE switch?

In 2003, IEEE formulated the first generation of PoE technical specification 802.3AF. Since PoE technology was originally used to power IP phones and remote cameras, the power required is not high. Therefore, in the 802.3AF specification, two of the four copper wires of the Cat3 twisted pair are used to achieve a remote power supply. Because the twisted pair of copper cables will have a significant voltage drop when transmitting large currents, the 802.3AF specification defines the power level of the PoE power supply switch port and the power level of the terminal-powered device port respectively. For PoE switches, the power supply port voltage is between 44V-57V, and the power reaches 15.4W; the terminal equipment port voltage is between 37V-57V, and the power reaches 12.95W. This generation of PoE technology is also known as Type 1 PoE.

POE switch like: S2326TP-PWR-EI-AC

What is a PoE+ switch?

In 2009, the second-generation PoE technical specification IEEE 802.3AT named PoE+ was officially released. At this time, the industry has begun to generally use Cat5 coaxial cable, which enables PoE+ switches to provide more power to terminal equipment. The power supply voltage of the PoE+ switch port is between 50V-57V, and the power reaches 30W; the terminal equipment port voltage is between 42.5V-57V, and the power reaches 25.5W. While the power available from the ports has increased significantly, the 802.3AT specification still uses two copper wires for power because the cable quality has gotten better. This generation of PoE technology is called Type 2 PoE.

PoE+ switch like: S1720-28GWR-PWR-4TP-AC, S2700-9TP-PWR-EI-AC, S3700-28TP-PWR-EI-AC, S5700-24TP-PWR-SI-AC

What is a PoE++ switch?

In 2018, corresponding to the IEEE 802.3BT specification, the third-generation PoE technology named PoE++ officially appeared. With the advent of faster wireless access devices, the power level that requires a remote power supply from PoE++ switches has been further improved. PoE++ technology is divided into two categories, called Type 3 PoE and Type 4 PoE.

Type 3 PoE can use two of the four copper wires in a twisted pair to supply power like PoE and PoE+, or it can use all four copper wires to supply power like Type 4 PoE. Type 4 PoE explicitly uses four copper wires to pull power. Obviously, the more copper wire used to power it, the more power it can deliver.

The power supply voltage of the PoE++ Type 3 switch port is between 50V-57V, which is the same as the PoE+ port, but the power is doubled to 60W; the terminal device port voltage is also between 42.5V-57V like the PoE+ port, and the power is also doubled to 51W.

The power supply voltage of the PoE++ Type 4 switch port is slightly increased, between 52V-57V, the power is increased to 100W; the terminal device port voltage is between 41.1V-57V, and the power is increased to 71W. Even laptops and TVs can be remotely powered when using a Type 4 PoE switch.

PoE++ switch like: S5720-16X-PWH-LI-AC, S5720-28X-PWH-LI-AC, S5720I-28X-PWH-SI-AC, S5730-60C-PWH-HI

PoE vs PoE+ vs PoE++

PoE vs PoE+

PoE+ has the following advantages over PoE:

1. Higher power: PoE+ switches can provide 25.5W-30W of power per port, while PoE switches can provide 12.95W-15.4W of power per port.

2. Stronger compatibility: PoE and PoE+ switches assign levels from 0-4 according to how much power is needed, and when a power supply device is connected to a power supply device, it provides its class to the power supply device so that the power supply device can provide it with the correct amount of power.

3. Further cost reduction: This simpler PoE+ uses standard cabling (Cat 5) to work with ordinary Ethernet interfaces, so no “new wire” is required.

4. More powerful: PoE+ only uses CAT5 network cable, which has 8 internal wires, which reduces the possibility of impedance and reduces power consumption compared with 4 wires of CAT3. In addition, PoE+ allows network administrators to provide greater functionality, such as providing new remote power diagnostics, status reporting, and power supply management.

PoE / PoE+ vs PoE++

The main differences between IEEE 802.3bt and IEEE 802.3af/at are as follows:

1. IEEE 802.3bt triples the maximum power of Power Sourcing Equipment (PSE) from 30 W to 90 W, and increases the Powered Device (PD) power level to 71.3 W.

2. IEEE 802.3bt increases the number of classes supported from 4 to 8.

3. The IEEE 802.3bt standard provides many new features and functions, such as supporting efficient 4-pair power transfer, and supporting channel definitions for 2.5 Gbps, 5 Gbps, and 10 Gbps PoE operation.