Power over Ethernet (PoE for short) is a local area network (LAN)-based power supply technology, which can transmit power and data to the devices through the network cable in the Ethernet. The application of this technology can greatly reduce operating costs and save operating time. As more and more devices are deployed on the network, the scenarios vary greatly, and the deployment time varies. Therefore, it is the best choice to provide remote power supply through PoE switches. At present, there are various switches based on PoE technology on the market, mainly including PoE switches, PoE+ switches, and PoE++ switches. And for these switches, do you know what are the differences between them?
What is PoE? And what is a PoE switch?
PoE (also referred to as the IEEE 802.3af standard) is a new standard issued by the IEEE 802.3 working group in 2003 based on Power over Ethernet systems. This standard stipulates that the powered device (PD), such as a VoIP phone, only needs to use the twisted pair in the same network cable during the power receiving process, and its PoE power consumption can reach up to 12.95W. Since PoE technology was originally used to power IP phones and IP cameras, the required power is not high. Therefore, in the 802.3AF specification, two of the four copper wires of the Cat3 twisted pair are used to realize PoE.
A PoE switch is an application based on PoE technology. It is a switch that can simultaneously provide power and data transmission for the receiving terminal through a network cable, it belongs to a power sourcing equipment (PSE). Since 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 switch port and the power level of the powered device port respectively.
For PoE switches that meet the 802.3af standard, the port voltage is between 44V-57V, and the maximum power can reach 15.4W. The powered device port voltage is between 37V-57V, and the maximum power can reach 12.95W. This generation of PoE technology is also known as Type 1 PoE.
What is PoE+? And what is a PoE+ switch?
PoE+ (also referred to as the IEEE 802.3at standard), as an upgrade to PoE technology, is a PoE technology standard released in 2009. With the wide application of PoE technology, some powered devices such as wireless APs require far more power than 12.95W. In order to solve this problem, the IEEE 802.3 working group released PoE+ technology designed to provide higher power for devices. At this time, the industry has begun to generally use Cat5 coaxial cables, which enables PoE+ switches to provide greater power for terminal equipment.
The PoE+ switch is similar to the PoE switch we mentioned above, and it also supplies power to PoE terminal devices through a network cable. The difference is that the maximum power supply of each port of the PoE+ switch is 30W, and the power supply voltage is 50V-57V. The maximum power received by the powered device can be increased to 25.5W, and the voltage can be increased to 42.5V-57V. Although the power provided by the port has been greatly improved, because the quality of the cable has become better, the 802.3AT specification still uses two copper wires for power. This generation of PoE technology is called Type 2 PoE.
What is PoE++? And what is a PoE++ switch?
With the continuous development of the PoE application market, the family of the IEEE 802.3 standard ushered in a new member in 2018: the IEEE 802.3bt standard. So far, PoE++ technology has emerged as the times require. With the emergence of faster wireless access devices, the power level required for remote power supply of PoE++ switches has been further improved. Under the IEEE 802.3bt standard, PoE++ technology is divided into two categories, namely Type 3 PoE and Type 4 PoE.
Type 3 PoE can use two twisted pairs of four copper wires to supply power like PoE and PoE+, or it can use all four copper wires to supply power like Type 4 PoE, which can provide power up to 51W to the powered device. Type 4 PoE clearly uses all four copper wires to supply power, and the input power of the powered device can reach 71W. Obviously, the more copper wire used to supply power, the more power can be delivered.
In addition, there is also a PoE technology based on the IEEE 802.3bt standard called uPoE (universal power over Ethernet) on the market. This technology is proprietary to Cisco, and its working mode is similar to that of Type 3 PoE technology, which can provide 51W of input power for the powered device. Therefore, some people in the industry also regard uPoE as PoE++.
The PoE++ switch is an upgrade to the PoE switch and PoE+ switch. 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 powered device port voltage is also between 42.5V-57V like the PoE+ powered device 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, and the power is increased to 100W. The powered device port voltage is between 41.1V-57V, and the power is increased to 71W. Even laptops and TVs can be powered remotely when using a Type 4 PoE switch.
PoE switch VS PoE+ switch VS PoE++ switch
Refer to the table below to view the specific parameters of PoE switch vs PoE+ switch vs PoE++ switch.
|Type 3/ UPOE
|Max Input Power (PD)
|Max Output Power (Switch)
|Output Voltage (Switch)
|Input Voltage (PD)
|Supported Pair Mode
|2 Pairs, 4 Pairs
|Supported Cable Types
How to choose a PoE switch compared with PoE+ switch and PoE++ switch?
From the previous introduction, we can see that PoE switches are different from PoE+ switches and PoE++ switches in terms of power supply and working mode. These differences will also have a corresponding impact on their respective applications.
A PoE switch based on the 802.3af standard has a power supply of no more than 15.4W per port. It can be connected to VoIP phones, sensors, measuring devices, wireless APs, static surveillance cameras and other terminal devices. The PoE+ switch can support higher-performance movable zoom cameras, wireless APs with six pairs of antennas, IP phones and more. Type 3 PoE switch with higher power supply capacity can support the connection of video conferencing system accessories and the management equipments of building system and so on. Type 4 PoE switch can support devices with higher power consumption requirements such as notebook computers and TVs.
When using a PoE switch, it should be noted that some network ports on a PoE switch support Type 1 PoE, some network ports support Type 2 PoE, and some network ports support Type 3 PoE or Type 4 PoE levels. Using a high-spec PoE port can meet the power requirements of a low-spec PoE port, but not vice versa. The current PoE power supply mainly uses Cat5e cable. In the future, the power demand for remote equipments will be further increased, and PoE switches will also be better developed.
With the continuous development and improvement of Power over Ethernet technology, network switches based on PoE technology have also been developed and updated from the original PoE switch to the latest PoE++ switch. In this article, we briefly compare the power supply modes and application types of PoE switch, PoE+ switch and PoE++ switch, hoping to give you some reference when purchasing PoE switches.
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