Power over Ethernet (PoE): the Fact File

The proliferation of IP-connected network devices in the enterprise has not only driven the need for faster data rates, but also increased power. This has thrown the door wide open for power over Ethernet (PoE).

PoE allows connected devices to share data and power connectivity over a single copper Ethernet cable—streamlining infrastructure and simplifying operations. While PoE has been part of the enterprise network since 1999, its capabilities and importance have taken big leaps forward in recent years with the development of higher-wattage PoE devices. These devices include common enterprise fixtures such as desktop telephones, security cameras, video monitors and wireless access points for Wi-Fi or in-building wireless services, among others.

With today’s advanced PoE technologies and devices, enterprise networks no longer need to run a separate ac (alternating current) power feed to every connected device. And that’s just the beginning. The benefits of PoE also include better-designed electrical safety features, better device management and lower cost of installation and maintenance.

Whether it’s Wi-Fi access points, security cameras, LED lighting, IP phones, RFID security or building management systems, the increasing range of PoE devices means there is a great opportunity for the Enterprise to leverage remote power and better manage infrastructure-related expenses while using existing cabling. Learn how, now.

PoE-FF-telephone-illustration

Powering of telecommunication devices over twisted-pair cabling is as old as the telephone
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What is PoE and how does it work?

PoE1 is a system for safely transmitting electrical power and data to remote devices using standard Ethernet cabling, Category 3 and higher. PoE works by converting the mains power supply into a low-voltage supply, then transmitting the power over structured cabling to PoE-enabled devices. The system is designed to prevent data and power signals from interfering with each other. Power is transmitted on the data conductors by applying a common voltage to each pair. Because twisted-pair Ethernet uses differential signaling, this does not interfere with data transmission. As a result, PoE is able to transmit both power and data signals without disrupting the data signal.

While signal interference is eliminated, some power dissipation is inevitable. For example, systems meeting the PoE 802.3af-2003 standard introduce 15.4 watts of power on the cabling, but only 12.95 watts can be expected to be received by the powered device. The good news is that, as PoE-connected devices evolve, the industry standards needed to support them have evolved as well. See Chapter 4.1 for more.

By using communications cabling to deliver remote power, PoE enables cost-effective power delivery to a wide range of devices. Other advantages include:

  • Smaller size of cables and connectors (versus ac line power) enables higher density
  • Continuous monitoring of the circuit for faults and other operating conditions
  • Low-voltage cabling can be installed as part of the ITC network for safer, lower-cost installations
  • Improved control and operation of devices for better facility management
  • Synergies between power delivery and communications enable intelligent infrastructure
  • UPS backup, enabling robust and reliable operation

PoE applications, markets and trends

According to the technology research and consulting firm The Building Services Research and Information Association (BSRIA), “worldwide PoE shipments are expected to grow at a compound annual growth rate (CAGR) of around 11-13% until 2023, exceeding 180 million ports sold yearly by the end of the period.”2

The evolution of PoE: standards, types and classes

The evolution of PoE technology mirrors the evolution of the devices it supports—from its precursor standard powering devices such as telephones, to the first PoE standard in 2003, to the latest IEEE 802.3bt standard4 that supplies at least 71 watts over structured cabling. It is not uncommon for the introduction of various connected devices to predate the standards.

Table 2: Operational characteristics of PoE by standard, type and class

Table 2: Operational characteristics of PoE by standard, type and class

PoE cabling design and deployment

Over the past decade, PoE has been seen as a key powering strategy—allowing network managers, installers, and integrators to use structured cabling to provide both power and data to many of their network devices. While the ability to run low-voltage power and data over the same cable could significantly simplify deployment and management of PoE networks, planning and designing them to achieve the best balance of cost, performance and manageability can be tricky. Engineers must consider several key variables. Key factors that affect and influence the efficient design and operation of your PoE network include:

  • Channel topology: cable pathway infrastructure
  • Managing thermal loads: cable bundling, spacing and lengths
  • Selection of cables, cords, and connectors

Cabling and connectors

Monitoring PoE distribution over structured cabling

As we have seen, cabling standards in TIA, ISO/IEC and CENELEC establish recommended cable bundle sizes based on environment and cable categories. Addendum 1 of the ISO/IEC 18598 (AIM standard) addresses the need to document cable bundle sizes and the power levels of each cable in the bundle.

Testing what’s next

Conclusion

The recent introduction of new connectivity options—Wi-Fi 6, 5G, shared spectrum and more—has helped increase the deployment of converged IoT and OT edge devices such as IP security cameras, LED lighting and 4K/HD digital signage. Additional edge devices include point-of-sale units, along with intelligent building management systems and sensors such as access control (smart locks), location services, fire detection and evacuation. Meanwhile, 5G-enabled smart home systems are beginning to gain real traction in the market, as well. Due to its efficiency, versatility and safety, power over Ethernet (PoE) is the preferred technology for delivering power to these connected edge devices, wireless access points and more.

The latest 802.3bt power over Ethernet standard (also known as four-pair PoE or simply 4PPoE) stipulates support for a full 90 watts, deliverable via Category 6A cabling. Although older wireless access points (APs) tend to draw a minimal amount of power, some newer APs require more power to drive all their radios and provide power for devices connected via their USB ports. The number of PoE-enabled edge devices—such as HD/4K digital signage; pan, tilt and zoom (PTZ) cameras; and smart LED lighting—is expected to continue to increase in the coming years.

PoE will likely also be considered as increasingly important as a stable backup power source for converged edge devices where uptime is critical. For example, an HD camera may feed data to multiple applications such as security systems, people counting, machine learning (ML) analytics and occupancy sensors. By combining and centralizing power and data at the network switch with dedicated power circuits, PoE simplifies and automates troubleshooting and management.

Yet, even as it simplifies and streamlines the network infrastructure, designing a PoE network that provides the best balance of performance, cost efficiency, reliability and scalability is anything but simple.

In the preceding chapters, we’ve provided an overview of some of the key concepts and considerations, which might be helpful to keep in mind as you design, grow and integrate your PoE system into the broader enterprise network. Admittedly, this is a high-level overview. We hope you will take advantage of the links to other assets that afford a deeper dive into specific issues.

And, as always, you’re never alone; CommScope is here to help guide and advise you—helping you plan and prepare for what’s next.

Further information

What’s Driving the Future of PoE?

Power over Ethernet advances go beyond more powerful network switches and support for in-building wireless. Learn what's in store for your network's PoE future.

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