Things You Should Know About PoE Network

With the development of networking, local power is not always accessible for wireless access points, IP phones, and other network devices that may be deployed in ceilings, lobbies, stairwell, and other obscure areas. Adding power outlets near these devices may be extremely difficult and costly. But why not provide these devices network connection and power in the same cable? In response to this need, IEEE developed IEEE802.3af to standardize a system which is called power over Ethernet (PoE) to supply low voltage power to networked devices via communication lines. In the following paragraphs, more information about PoE network will be discussed.

Basic Concepts of PoE Network

Power over Ethernet (PoE), also called as active Ethernet, is a technology for wired Ethernet LANs (local area networks) allowing the electrical current necessary for the operation of each device to be carried by data cables rather than by power cords. There are three basic components in PoE system—PSE, PD and the cable itself. PSE which stands for power sourcing equipment like PoE switch is designed to deliver power to the cable, while PD (powered device) receives power from the cable. And the cable will help transmit the electrical power and data signal. In general, there are two methods of PoE. One is mid-span, and the other is end-span.

Working Principle of PoE 

The electrical current must go into the data cable at the power-supply end (PSE end), and come out at the device end (PD end), which can keep the current separated from the data signal so that neither of them interferes with the other. The current enters the cable by means of a component called an injector. If the device at the other end of the cable is PoE compatible, then the device will function properly without modification; otherwise a component called a picker or tap must be installed to remove the current from the cable.

Advantages of PoE

Why is PoE more and more widely used in many devices? Some of the advantages with PoE over other technologies may be:

• 1. Time and cost saving: It is the primary advantage. By reducing the time and expense of having electrical power cabling installed, network cables do not require a qualified electrician to fit them, and can be located wherever they are needed most.
• 2. Great flexibility: Without being tethered to an electrical outlet, devices such as IP cameras and wireless access points can be located regardless of area restriction. Besides, they can be repositioned easily if required.
• 3. Safety: PoE network is designed so safe and intelligent that it can protect network equipment from overload, under-powering, or incorrect installation.
• 4. Reliability: PoE power comes from a central and universally compatible source instead of a collection of distributed wall adapters. In addition, with the backing-up of an uninterruptible power supply, the PoE network can be operated more stably.
• 5. Scalability: Due to the electrical power available on PoE network, the installation and distribution of network connections can be simple and effective.

Applications of PoE

PoE has many applications, but the key areas are:

• VoIP phones—It is the original PoE application. Using PoE means phones have a single connection to a wall socket, and can be remotely powered down, just like with the older analog system.
• IP camera—Nowadays, PoE is ubiquitous on networked surveillance cameras, where it enables fast deployment and easy repositioning.
• Wireless—Wifi, Bluetooth APs and RFID (radio frequency identification devices) readers are commonly PoE-compatible, to allow remote location away from AC outlets, and relocation following site surveys.

Summary

Like all technologies, the advent of PoE has greatly enhanced the effectiveness of network. There is no doubt that PoE will become increasingly important in the future. The above statements only briefly explain PoE from basic concept, working principle, advantage and application. There is still more knowledge about it we should learn.