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Used PoE switches for so long, but did you know its glorious "evolutionary history"? Feng Runda, the world's leading provider of transmission products & services, today explained to you the "Previous Life" of PoE switches.
1, PoE evolution history
The PoE switch is based on the existing Ethernet Cat.5 cabling, and transmits data to the IP terminal equipment (IP phones, wireless APs, network cameras, etc.) and provides DC-powered switches. PoE switches exist because they can meet the power needs of IP devices.
The PoE switch is actually an evolutionary history of security power. It can be roughly divided into five phases: network cable + power line, fake PoE, non-standard PoE, IEEE802.3af standard, IEEE802.3at standard. 
Network cable + power cable is an old-fashioned IP cabling, and is the most primitive wiring method, not only inconvenient wiring, but also to maintain many hidden dangers later; false PoE power supply is a PoE combiner to merge DC power into the network cable, there is a great safety Hidden trouble; non-standard PoE power supply does not automatically detect the link, regardless of whether the IP terminal supports PoE will give it power, if the IP terminal does not support PoE power supply, it is very likely to burn the network port; IEEE802.3af power supply standard was born in 2003, defined The PoE switch port provides 15.4W of power; IEEE802.3at, which emerged in 2009, provides greater 30W power requirements based on 802.3af compatibility.
2, PoE power supply system
With the rapid development of network monitoring, an intelligent power supply technology is urgently needed to solve the problem of data and power transmission. At the same time, it has the advantages of convenience, speed, and stability. This technology is none other than PoE power supply. The PoE power supply system includes a power-supply-side device PSE and a power-receiving-end device PD, both of which establish a connection based on the IEEE802.3af standard regarding the connection status, device type, power consumption level, etc. of the power-receiving device PD. Enables the PSE to supply power to the PD over Ethernet. 
PoE power supply system can ensure the safety of existing structured cabling, ensure the normal operation of existing networks, and minimize the cost.
3, PoE power supply advantages 
Simplified cabling: PoE power is actually a line that transmits data and power at the same time, eliminating the need for costly and time-consuming network devices that require expensive power and time to install power supplies.
Convenient security: PoE power supply equipment will only supply power to the equipment that needs power supply. Only when the power supply equipment is connected, the voltage will exist in the Ethernet cable, thus eliminating the risk of leakage on the line and at the same time, it can be safely mixed on the network. Original devices and PoE devices.
Facilitate remote management: Like data transmission, PoE can monitor and control the device by using Simple Network Management Protocol (SNMP).
Adaptable: All IP devices, such as Internet phones, wireless base stations, network cameras, hubs, computers and other devices can use PoE technology.
4. Selecting a suitable PoE switch The selection of a PoE switch needs to be analyzed according to specific conditions and requirements. Generally, two principles are followed: how much power is needed to supply power to a device, and how many devices can be powered.
PoE switches have different output power due to their different power supply standards. IEEE802.3af standard, PSE end output is 15.4W, PD end can obtain 12.95W; IEEE802.3at standard, PSE end exports 30W, PD end can obtain 25.5W. Due to the loss of transmission wires, the IEEE802.3af standard PoE switch supplies power to devices with a maximum power of 12.95W. Similarly, IEEE802.3at standard PoE switches can supply power to devices with a maximum power of 25W or less.
An important indicator of the PoE switch is the total power of the PoE power supply. For example, a full-power PoE switch with a 24-port PoE switch has a total power of 400 W. According to the IEEE802.3af standard, 400/15.4>24, full-load 24-port power supply can be provided. According to the IEEE802.3at standard, 400/30>12, at least 12 ports can be filled.
The selection of high-quality, high-efficiency PoE switches requires not only the above problems, but also the number of interfaces required, the availability of fiber ports, the absence of network management, and the rate (10/100/1000M). In addition, when using PoE, be sure to use a standard network cable.
Feng Runda analyzes the development history of PoE switches and past and present lives
With the planning of projects such as “China of Peace†and “Smart City†and people’s increasing security awareness, the installation scale and radiation area of ​​video surveillance are increasing. The scope of the project involves the entire city and the camera reaches tens of thousands. One. Large-scale network monitoring has led to a large number of applications and popularization of PoE switches, and the use of PoE switches does bring a lot of convenience to the monitoring project.