What is Power over Ethernet(PoE) – A Detailed Guide

You may have come across the term PoE while dealing with network configuration. These days, more devices rely on Power over Ethernet than they used to. You may want to do the same while setting up a CCTV camera system or FWA. This guide will help you understand the different aspects of Power over Ethernet (PoE), how it works, and the various standards you should be familiar with. We will start with the basics.

What is Power over Ethernet?

Power over Ethernet, better known as PoE, is a technology that allows Ethernet cables to supply power to a connected device. The copper wire inside the Ethernet cable will simultaneously carry network signals and electrical power. Power over Ethernet (PoE) is widely used to reduce the number of cables while keeping equipment running as it should.

Let’s take the case of a security camera that you have placed outdoors. Typically, you would need a network (Ethernet) cable and a separate power delivery cable to keep the camera running. However, you can remove the power delivery cable from the equation by adopting Power over Ethernet. With a single cable, you can take care of data and power.

VoIP phones were practically the reason behind the invention of Power over Ethernet. As you know, these phones needed Ethernet cables to transfer data. However, they also needed an extra cable to offer electrical power. So, engineers thought about combining data and power delivery options into a single cable, and PoE was born.

There are multiple ways Power of Ethernet can benefit network environments.

How Does PoE Work?

Power over Ethernet uses a number of technologies to ensure that the target power receives both the data and power resources through a single cable.

The first aspect here deals with injecting power into the Ethernet data cable. It can be done in two ways: endspan and midspan. In the endspan method, the power injection happens at the switch level, and the switch is optimized to deliver sufficient/required power to the powered device (PD). Using midspan mode, however, you can add power injection using another switch even if the original network switch does not offer a power delivery option.

These days, network switches are smart enough to talk to the powered devices to confirm compatibility with Power over Ethernet. It is also essential to understand that the data signals and power do not interfere with each other, thanks to the use of differential signaling. You can also use one of the three major techniques to route power through Ethernet.

• In the Alternative A technique, the same wire pairs may be used for power and data.
• In the Alternative B technique, wire pairs are reserved for data and power delivery.
• In the 4PPoE technique, all four wire pairs on the Ethernet cable can handle data and power.

These days, modern PoE devices use the 4PPoE technique, but the Alternative A technique is also popular.

Power Over Ethernet Standards

Like other technologies, PoE also uses multiple standards. We have already established that PoE is used to deliver power to a variety of devices. Naturally, Power over Ethernet standards mostly have to deal with how much power a PoE connection can handle/deliver.

• IEEE 802.3af is the original PoE standard, often called Type 1 and PoE. It was designed to power VoIP phones and low-power cameras. They could handle a maximum power of 15.4W at the power supply level.

• IEEE 802.3at is an enhanced version, popularly called Type 2 and POE+. They were designed to power slightly higher-power devices like wireless access points and cameras, offering source-level power of 30W.
• IEEE 802.3bt is the latest standard, often called POE++, Type 3, and Type 4. This standard allows PoE to power-hungry devices like wireless APs and automation.

Here’s a quick cable if you need some extra information:

Like Ethernet cables, PoE systems are also backward compatible for the most part. However, you can expect maximum power delivery limits of the device at a lower standard. For instance, when you connect a PoE+ to PoE++, the maximum power at the PSE level would be 30W, not 60W.

What devices use Power over Ethernet (PoE)?

Here are some devices that use Power over Ethernet.

• VoIP phones
• IP cameras (including PTZ cameras)
• Wireless access points (WAPs)
• Network routers and small switches
• IPTV decoders and digital signage displays
• Intercom and public address (PA) systems
• Access control panels and card readers
• Smart lighting systems (LED lighting)
• Environmental and IoT sensors (temperature, humidity, occupancy)
• Building management and automation devices
• Thin client computers and laptops
• Point of Sale (POS) terminals and retail kiosks
• Wall clocks with NTP synchronization
• Conference room AV equipment (video conferencing systems)
• Factory automation devices (HMI terminals, gateways)
• Traffic cameras and transportation monitoring devices

As Power over Ethernet continues to grow, more devices and industries are adopting the tech.

Benefits of Power over Ethernet (PoE)

Let’s look at the significant advantages of using Power over Ethernet (PoE) instead of conventional methods for power delivery.

• Convenience: Since PoE lets you deliver data and power through a single cable, you can cut down how much you spend on network infrastructure. In general, fewer wires mean more convenience, too.
• Scalability: Though there are distance-based limitations, PoE can make your network setup scalable without worrying about the availability of power outlets. PoE-based Wi-Fi access points can improve your network coverage and speed by a long shot.
• Easy Control: Network managers appreciate the additional control they get while using Power over Ethernet instead of separate power delivery options. Since you can manage everything from a single switch, automations also become easier.
• Easy Deployment: As long as you have PoE-compatible devices, setting up network devices and other pointers is easy. You can deploy the devices into your existing networks, too. These days, the security aspect of PoE is also impressive.

We must also mention some potential issues. It’s not all sunshine and rainbows. Because a network switch has access to power delivery, it may lead to some security concerns as well. Also, the maximum power you can deliver via PoE is 100W, and it requires the latest standards. Similarly, you cannot expect the same power beyond 100 meters. PoE switches may take a hit on performance due to overloading.

Conclusion

We have now covered almost everything you need to know about Power over Ethernet. There is enough info to help you get started with a home-based project or a PoE system for a small office. Ensure that you really pay attention to PoE standards and specifications before proceeding with purchases.