Using Power over Ethernet for UC: Pros and cons

Deploying Power over Ethernet is an intriguing option for unified communications, but the standard, which enables the same Ethernet cables to transmit both electrical power and data to a compliant device, isn’t for every situation.

Implementing PoE for UC requires power sourcing equipment (PSE) and powered devices (PDs). For UC, PSE includes network devices, like switches, splitters and routers, while PDs include VoIP phones, IP cameras and video phones.
Let’s examine where using Power over Ethernet for UC can work and where it might not be viable.

The benefits of PoE for UC
Implementing PoE can modernize UC in terms of information exchange, number of deployed devices and cost of maintenance.
Network infrastructure optimization
PoE network infrastructure supports uninterrupted communication and performs centralized power management through a smaller number of cables. Transferring electrical power and data through the same pair of cables eliminates the need to deploy excess electrical wiring and charging points in an enterprise. Non-PoE-enabled traditional network devices can even connect to PoE networks through splitters or injectors. This helps enterprises improve their LAN designs and places less load on the system.
Central management
PoE network infrastructure can provide sufficient range, security and quality of service through central management of PDs, among them VoIP phones, IP cameras and associated non-PoE devices. PoE switches are equipped with a PD manager feature that lets them automatically detect the current status of connected devices and, if necessary, fix them quickly. PoE power sourcing devices can also automatically detect deliverable power to end devices, avoiding excess power loss. To further minimize downtime, PoE switches outfitted with uplink provide additional connection capabilities. Other features include remote management, additional ports and high-bandwidth support. PoE unmanaged switches are also commercially available.
Power over Ethernet for UC gives enterprises a wide choice in how they design their internal networks. Connected devices do not rely on the position of sockets, charging points or power sources to operate. Power outages cannot interrupt internet access, overcoming one of the major limitations of Ethernet. There is no power wastage when PoE devices go offline. In addition, watchdog functionality cuts off power to disabled devices to ensure safe restoration.
Safe technology
PoE uses low-voltage signals from 40 V to 57 V to generate low-ampere direct current (DC). Implementation of DC PoE, instead of alternating current PoE, eliminates the chances of interference and any chances of a physical electricity hazard. To maintain safety, PoE uses a handshake and power negotiation procedures to connect devices in an enterprise network infrastructure. Power is not wasted in these cases. The switches, splitters or injectors that connect UC devices enable a microampere current at each port. Such UC devices and wiring systems are physically safe for repeated use in enterprises. PoE’s DC power output ranges from 15.5 watts to 90 W, depending upon the standard chosen.
Deploying PoE equipment over network infrastructure doesn’t directly impact enterprise security. The chances that hackers focus their attention on PoE-compatible devices are low; there are far richer targets to be found in other legacy network technology. There is the chance that a hacker might try to interrupt the delivery of electrical power as part of a larger attack on data, but intelligent PoE devices seamlessly integrate with network security tools and analytics software to offer safety and reliability.
Uninterrupted connectivity
With PoE, dedicated wires within the Ethernet cable carry internally generated current, while others are used to transmit data to UC devices. As a result, there is no chance of interference or signal mixing that could hinder unfettered internet access. PoE-powered devices can support data rates from 10 to 1,000 Mbps; Type 4 devices can support up to 5 Gbps. If a PoE device becomes unresponsive or goes offline, PoE switches detect it; the affected device is automatically reset without human intervention.
Cost savings
UC managers plan PoE budgets based on a number of factors, among them standards, ports, number of devices supporting other components, range, power and cost per cable. With PoE, the need to install extra power cables and associated devices is eliminated, saving both energy and costs. Power over Ethernet for UC is particularly beneficial in remote offices, locations with frequent outages or difficult terrain — far to reach, high altitude, near water bodies, deserted areas, etc. PoE also reduces recurring costs generated as part of an enterprise migration. Less bulky network infrastructure results in low installation, distribution and maintenance costs — along with less manual input.

Where PoE might not work for UC
For all its benefits, deploying PoE for UC also has challenges, such as the following.
Low range
PoE is unsuitable for large-scale enterprises that deploy multiple networks throughout their locations. PoE cable has a fixed but low range of 100 meters (m). More powerful PoE standards extend the cable range but deliver inefficient DC output. A PoE repeater can extend the range of PoE network infrastructure beyond 100 m but adding repeaters makes the network bulkier.
High power consumption
Video conferencing, live meetings, long calls and large file storage consume high amounts of electrical power. Certain PoE standards deliver less power per port. It’s not uncommon to find devices that require more electrical power than PoE can provide. Data transfer speeds and call quality can both be diminished as a result.
Capex and other costs
Enterprises planning to upgrade their UC services may not want to get rid of their older, analog devices. Buying equipment that supports newer PoE standards — among them PoE++ or High-Power PoE — is more expensive.
Management and provisioning
Calculating the PoE budget is critical in a UC environment. Each port in a PoE switch provides a limited but fixed amount of power. Managers must design a PoE budget that ensures that the number of supported UC devices doesn’t exceed the available power.
Compatibility and compliance
For Power over Ethernet for UC to be effective, PoE devices must be compatible with hardware, standards, voltage, length of cable and the power output of the network infrastructure. Legacy communication devices may not be compliant or compatible with PoE switches. Connecting noncompatible or noncompliant PoE requires extra hardware, resulting in increased PoE deployment costs and perhaps interference with already operational traditional networks.
Heat dissipation
PoE devices heat up due to current flow. Aluminum cable, due to poor electrical conductivity compared with copper cables, generates more heat dissipation. PoE devices supporting higher-speed standards are prone to even higher amounts of heat and power loss. Companies can counteract some of these issues through the proper choice of HVAC systems and cabling.

PoE vs. PoDL: What’s the difference?
Power over Ethernet and Power over Data Line (PoDL) are often misunderstood as the same technology.
While IEEE recognizes PoE, it does not standardize PoDL.
PoDL relies on Single-Pair Ethernet (SPE), the technology that transfers and receives data through a single pair of cables. When the same SPE transmits power, the technology now functions as PoDL. PoDL, however, is not limited to Ethernet-like PoE; PoDL can use twisted or coaxial cable as well.


IEEE recognition
IEEE 802.3af-2003 (Type 1 PoE) IEEE 802.3at-2009 (Type 2 PoE+) IEEE 802.3bt-2018 (Type 3 and 4 PoE++ or universal PoE)
Not recognized

Physical element
Ethernet cables
Ethernet, twisted-pair or coaxial cables

Internal operation
PoE transfers data and power in separate wires
PoDL transfers data and power in the same wire but in different directions

Least cable pair requirement
Two pairs of cable
One, similar to SPE

Number of electrical cable requirements
More than PoDL
Less than PoE

Interference chances
Slightly higher

Implementation status
Large-scale implementation

Venus Kohli is an electronics and telecommunications engineer, having completed her engineering degree from Bharati Vidyapeeth College of Engineering at Mumbai University in 2019. Kohli works as a technical writer for electronics, electrical, networking and various other technological categories.