Power over Ethernet (PoE) has transformed the way modern networks are designed — offering the dual benefits of data and power transmission over a single cable. This dramatically reduces installation costs and simplifies network planning by removing the need for separate electrical outlets near devices. But as networked devices continue to demand more power, optimizing how that power is allocated becomes critical. This is where Autoclass (AUC), a feature of the IEEE 802.3bt PoE standard, plays a game-changing role.

Why IEEE 802.3bt Is a Big Leap Forward

Introduced in September 2018, the IEEE 802.3bt standard was developed to meet the increasing power needs of modern devices such as CCTV cameras, Wi-Fi access points, thin clients, 5G equipment, and more. It builds on earlier standards — IEEE 802.3af (Type 1) and IEEE 802.3at (Type 2) — by delivering much higher power using all four wire pairs in an Ethernet cable. This enables power levels up to 90W at the Power Sourcing Equipment (PSE) and 71.3W at the Powered Device (PD).

The Role of Autoclass in Optimizing Power Use

In older PoE standards, the PSE allocated power based on preset classifications, often overestimating the actual need of the PD. This approach was inefficient, particularly when using shorter cables or higher-quality Ethernet like Cat6, where actual power loss is minimal.

Autoclass, a key feature in IEEE 802.3bt, solves this by allowing PDs to report their true maximum power requirement. During the classification phase, a PD signals its intent to use Autoclass by briefly adjusting the classification current. Once the device powers up, it draws its maximum required power, enabling the PSE to allocate just enough — no more, no less.

The result? More available power across the switch, reduced energy waste, and a more scalable, cost-effective PoE deployment.

Real-World Examples: Power Savings with Autoclass

Let’s consider two scenarios that highlight Autoclass optimization:

1. Using High-Quality Copper Cable

A PD requires 65W. Without Autoclass, the PSE defaults to allocating 90W (Class 8). With Autoclass, the PSE correctly adjusts to supply just 68.82W, saving over 21W per port. In an 8-port setup, that’s a saving of more than 160W.

2. Using Lower-Cost Copper-Aluminum Cable

With a 70W PD, Autoclass reduces unnecessary allocation from 90W to 73.78W, saving nearly 17W per port. Across 8 ports, that’s a total of 134W in power savings.

PoweredEthernet™ Products with Autoclass Support

Infomart’s PoweredEthernet™ IEEE 802.3bt modules — including the PEM9300BT (Class 8), PEM6300BT (Class 6), and PEB9300BT all-in-one PD boards — feature optional Autoclass support. This empowers system designers to maximize efficiency and lower costs while ensuring robust and reliable performance.

Additionally, these products offer Maintain Power Signature (MPS), another IEEE 802.3bt feature that allows ultra-low standby power consumption without disconnection risk — plus built-in wall adapter redundancy, all with minimal external components.

Conclusion: Autoclass is the Smart Choice for Smart Networks

Autoclass is more than a technical upgrade — it’s a critical enabler for modern, power-efficient networks. Whether you’re deploying a high-density PoE switch or designing next-gen connected devices, leveraging IEEE 802.3bt with Autoclass ensures optimal performance, significant cost savings, and a future-ready infrastructure.