You’ve Got the Power—Ensuring Interoperability for Power Over Ethernet Devices


This article was co-authored by Mark Mullins of the Ethernet Alliance.

 

What do designers, integrators, and technology users want? Interoperability! When do they want it? How about, oh, yesterday?

No one wants a mobile phone that can communicate only with other phones from the same manufacturer or provider. It’s the whole raison d’etre for organizations like IEEE 802, which standardized the underlying technologies of Ethernet, Wi-Fi, and Power over Ethernet (PoE).

Systems integrators seem to grasp the value of standardization—in a recent Ethernet Alliance survey, 93 percent reported only using or preferring IEEE 802.3-compliant PoE devices.

 

Figure 1. Survey results indicate system integrators prefer IEEE 802.3-compliant PoE devices. Image used courtesy of the Ethernet Alliance (click to enlarge)

 

Interoperability: The “Hello World” of PoE

Slate Magazine once compared coding to sorcery, with “Hello World” being the trick that wows the audience. It’s no different with PoE. Interoperability is PoE’s “Hello World,” where you plug in your device, and it just works. It makes the handshake happen between disparate vendors, allowing users to trust that their devices will play nicely together.

An interoperable technology allows customers to avoid unnecessary compromises, enabling them to choose the best products regardless of vendor. For example, a system designer may determine that one vendor’s offering might best meet a project’s requirements for an access point, while a different vendor’s camera best fits the security needs, but a third vendor’s switch that will power both may be the optimum choice for the existing network. How do you reconcile this mashup of products and solutions without interoperability?

This brings up a second benefit: being able to expand an existing network without requiring significant modifications or scrambling to find a now-discontinued model. Think back to recent supply chain disruptions where manufacturers had to scour the world over and pay through the nose for specific components or, even worse, spend months re-engineering a device to accept a different one. With today’s expectations for instantaneous connection and productivity, nobody has time for that.

A similar but distinct benefit is the ability to easily replace an existing PoE device that has failed or upgrade to a newer, better version of a product. Interoperability is the magic that makes it happen.

 

The Road to Interoperability

Though the destination may be the same—true interoperability—there are different schools of thought about how to get there. One approach is to hope that every vendor very carefully follows the IEEE 802.3 family of standards, which define electrical interfaces in great detail, thus ensuring all compliant devices seamlessly work together. But that’s often easier said than done.

Just like a systems integrator, PoE device designers typically integrate components like Ethernet interfaces, power management devices, and more from different vendors within a device. While these components are supposed to work together (and usually do), it’s still up to the manufacturer to determine how their finished product works with other devices.

In the case of devices requiring power from the network, also called a Powered Device or PD for short, testing can be performed by connecting the product with a variety of switches (commonly known as Power Sourcing Equipment or PSE) to ensure the device works properly. But even if it’s tested with dozens of PSEs, it’s impossible to test it with every potential PSE out there, let alone those that haven’t been introduced yet.

This approach works pretty well, yet it’s not guaranteed that all devices will work together. According to the Ethernet Alliance’s survey, more than one-third of PoE designers, integrators, and users report major or significant problems when integrating PoE devices.

 

Survey results indicate numerous challenges during PoE device installation

Figure 2. Survey results indicate numerous challenges during PoE device installation. Image used courtesy of the Ethernet Alliance (click to enlarge)

 

Part of this can be chalked up simply to confusion, as the term “PoE” is well-defined in IEEE 802.3 standards but is not a registered trademark, thereby permitting any vendor to self-proclaim PoE capabilities. Convoluting things even further, some vendors have adopted non-standards-based PoE branding, such as PoE+, PoE++, and UPOE, making it easier for field technicians and designers to quickly become confused about which device brands will interoperate without issues in their network.

To be clear, there are currently two approved IEEE 802.3 PoE standards:

Power over 2-pairs: IEEE 802.3at and IEEE 802.3af.
Power over 4-pairs: IEEE 802.3bt, which encompasses eight class levels for power negotiation.

 

Simplify With the Ethernet Alliance PoE Certification Program

Luckily, there’s a simple way to avoid all of this confusion. The Ethernet Alliance, a consortium of industry experts and manufacturers representing providers of ninety percent of PSE switching equipment, has stepped in with a PoE certification program. Aimed at bringing clarity and simplicity to the PoE space and enhancing the interoperability of devices based on IEEE 802.3 standards, it provides a test methodology for certifying products are compliant with IEEE 802.3 PoE standards.

The program provides a trademarked Ethernet Alliance Certified logo for use on products, packaging, and online documentation to easily identify certified PoE products intended to work together. In addition, the Ethernet Alliance Certified product registry is a publicly available resource for quickly and easily looking up any vendor’s certified PoE device.

 

PoE Certification Testing

The Ethernet Alliance Certified PoE process is defined by a 300-page test plan, using authorized third-party test labs and optional first-party testing with approved test equipment. Developed collaboratively by experts from multiple component manufacturers, PSE and PD designers, test equipment suppliers, and academics, this plan goes beyond what any single manufacturer could hope to develop.

Rather than testing by connecting to different devices to see if they work together, program testing measures the actual compliance of the device to IEEE 802.3 PoE standards. This testing may be conducted by PoE device manufacturers using the first-party test option or sending devices to third-party test labs, such as the University of New Hampshire’s Interoperability Laboratory (UNH-IOL) or UL Solutions. The Ethernet Alliance Certification Program includes physical layer testing of both PSE and PD devices and includes the Link Layer Discovery Protocol (LLDP) for all defined power classes.

 

Look for the Ethernet Alliance Certified PoE Logo

Equipment passing this rigorous testing process may be approved to use the trademarked Ethernet Alliance Certified PoE logo marks. It will be included in the public Ethernet Alliance Certified product registry. The simple, straightforward labeling makes it easier for customers to determine if a PD will work with a PSE, simplifying product evaluation, installation, and troubleshooting. Products are more likely to power up successfully when installed and continue operating properly, meaning less time spent troubleshooting and on the phone with support.

 

Survey results demonstrate value of PoE certification

Figure 3. Survey results demonstrate value of PoE certification. Image used courtesy of the Ethernet Alliance (click to enlarge)

 

Given that PoE always involves both a PD and a PSE, often from different vendors, avoiding the calls and attendant finger-pointing that troubleshooting frequently brings makes this an invaluable benefit. And users agree, too! The Ethernet Alliance survey found that more than 75 percent expected fewer problems with certified PoE devices.

This process also benefits PSE and PD manufacturers by replacing the need to expend resources on developing their own testing programs. By leveraging approved external resources such as UNH-IOL and UL, vendors can allow their engineering teams to concentrate on developing new customer features rather than testing. Fewer support calls on PoE issues also translate to lower costs and increased customer satisfaction.

 

Learn More About the Ethernet Alliance and PoE Certification

The robust Ethernet Alliance Certified test plan makes it less likely that a problem will go undiscovered before the product is launched. This lessens the chance of costly recalls or post-launch redesigns that can cause customers to lose confidence in a new product.

Taking advantage of the benefits that the Ethernet Alliance PoE Certification Program delivers is fast and easy. Learn more about the certification program now at the PoE Getting Started information page on the Ethernet Alliance website.

Industry Articles are a form of content that allows industry partners to share useful news, messages, and technology with All About Circuits readers in a way editorial content is not well suited to. All Industry Articles are subject to strict editorial guidelines with the intention of offering readers useful news, technical expertise, or stories. The viewpoints and opinions expressed in Industry Articles are those of the partner and not necessarily those of All About Circuits or its writers.



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