What is Power over Ethernet (PoE)?

Power over Ethernet (or PoE) is the distribution of electrical power to network devices over the same Ethernet cabling that connects them to the LAN. This simplifies the devices themselves by eliminating the need for electric plugs and power converters, and makes it unnecessary to install separate AC electric wiring and sockets near each device.

Many enterprises are beginning to rely on PoE to bring power over existing data cables for Wi-Fi access points, firewalls, IP phones, and other infrastructure throughout their networks.

The use of PoE has grown substantially since it was standardized by the IEEE in 2003, and its use will only grow in the coming years as new applications develop. According to Dell’Oro Group, the Power over Ethernet market is expected to grow at a rate of 13% per year from 2023 to 2028, reaching a value of $1.86 billion by 2026.

“There are many drivers for PoE technology. For example, if you look at WLAN access points, you’ve got a number of [wireless-spectrum] bands and higher speeds that require higher power,” says Sameh Boujelbein, Senior Research Director of Ethernet Switch Market Research at Dell’Oro. “The new generation of IP phones is adding telepresence features. If you look at surveillance cameras, you’ve got zooming features, you’ve got added analytics. All these new features require high power.”

How does Power over Ethernet work?

PoE transmits DC power over wires inside an Ethernet cable. In some variations, power and data travel on separate pairs within the cable, but in others they travel along the same copper wires. Because Ethernet uses differential signaling, power and data transmissions do not interfere with each other. technology is similar to what is known as Phantom power, Technology used by condenser microphones and the legacy Plain Old Telephone Service (POTS).

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This is appropriate because one of the first big use cases for PoE appeared about 20 years ago, when many enterprises started replacing those POTS lines with IP phones; PoE made it possible to roll out more power-hungry IP phones in a single location without the need for a separate dedicated power connection.

PoE networks consist of powered equipment– Basically, any device that receives both power and data from the network – simultaneously power sourcing equipment, Which provides electrical power to the network from an external power source.

Many Ethernet switches have the capability to serve as PoE power sourcing equipment, but you can also use injector For delivering power to parts of the network where the gear is not PoE-capable. PoE transmission distance does not go beyond 100m, so is said to be an injector or other PoE-enabled switch Midspan Device-Regular places with networks are a must.

Not all network devices are capable of being powered by a PoE connection. However, these devices can still receive data from that connection, and there is no risk of their network card being damaged by the incoming power: each PoE connection is tested before it attempts to power up the endpoint device’s capabilities. Handshakes for. you can also use a poe splitter That would separate power and data from the Ethernet cabling and distribute the former to a standard power jack.

PoE works over standard Ethernet cables that you probably already use for your network. The only catch is that for the Type 3 and 4 PoE standards that represent the current state of the art, you need an 8-pin Ethernet cable. Some older networks still use 4-pin, so check before proceeding.

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benefits of power over ethernet

The driving idea behind PoE was to eliminate the need for electrical outlet installation, especially in remote or inaccessible locations.

PoE promises:

  • Reduce deployment cost by up to $1,000 per device.
  • Minimize the need for an AC power adapter.
  • Simplify installation by allowing customers to install a single Cat5/5e/6 cable for both data and power.
  • Provide centralized power backup and management to customers.
  • Make it possible to reuse copper from old phone networks.
  • Easy to relocate equipment without make downtime.

“Energy savings is a big part of PoE specifically, but the standard really focuses on energy efficiency because it uses all four pairs [wires in] Ethernet Cat 5 cabling whereas previous versions of the standard used two,” said David Tremblay, chairman of the Ethernet Alliance PoE subcommittee and systems architect at Aruba Networks, an HPE company.

The latest standard maintains a power-signature level that supports lighting or IoT applications and acceptable standby performance when needed.

Another advantage, Tremblay said, is that PoE in combination with analytics software can let facilities-management teams determine which areas of buildings are unoccupied and save power by remotely turning off lights and HVAC equipment. .

An important and growing advantage of PoE is the deployment of Wi-Fi access points. Boujelbein said these devices are often placed in places where it is difficult to extend conventional power lines, such as behind ceiling panels.

Tremblay said the growth of wireless in places such as buildings, offices and sports arenas drives the need for PoE. “PoE makes wireless rollout more tangible.”

What are the different power over ethernet standards, and what is high power PoE?

PoE standards are divided into four parts Type, Which varies depending on the power capacity. The original IEEE PoE standard (802.3af-2003, now known as type 1) specifies how to deliver 15.4W DC power per switch port to each device over Category 3, 5, 5e, and 6 Ethernet cables up to 33 feet.

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The standard sets 15.4W as the maximum, but only provides 12.95W to reach devices because of power spread within the cable over distance. This loss does not affect the network performance of the devices’ 10/100/1000Mbps Ethernet links.

Over time newer devices require more power, so a new standard, PoE+ (IEEE 802.3at, or type 2), created in 2009, boosts the maximum power to 30W with devices reaching 25.5W.

The current standard, 802.3bt, increases the maximum power even more. According to Tremblay, this is expected to be the final PoE standard. It is divided into two different types: type 3, or UPoE, which can deliver 60W per port and 51W to devices, and type 4, or High Power PoE, which can deliver 100W from the source switch with 71.3W available to devices. This level of power is needed to sustain PoE-powered IoT rollouts.

Grand Challenge: Power over Ethernet Interoperability

The biggest challenge for PoE is ensuring interoperability.

Tremblay said the Ethernet Alliance’s Power over Ethernet (PoE) certification program can help enable faster PoE installations and avoid interoperability issues. Ethernet vendors including Analog Devices, Cisco, HPE, Huawei, Microsemi and Texas Instruments are part of the certification program.

But as new classes of devices evolve, industry players need to forge new partnerships with companies that offer certified devices, Dell’Oro Group said. “With the diversity of applications, come interoperability issues that dictate the need for testing and certification,” Büjelbein said.

Certified products range from component-level evaluation boards, to power-sourcing enterprise switches, to midspan PoE power sources. Details of certified products are available through the program’s public registry.

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