Power over Ethernet Standards, History, and Evolution

The difference between 802.3af vs. 802.3at (PoE vs. PoE+, respectively) is the amount of power delivered. The 802.3af PoE standard delivers 15.4 Watts to endpoint devices, while the more recent 802.3at PoE standard delivers 25.5 Watts to endpoint devices.

Power Over Ethernet History

802.3af (PoE)

The 802.3af Power over Ethernet standard was introduced in 2003 and would eventually support the initial explosion of IoT devices. 802.3af allowed installers to deliver power and data using one networking solution. It caused a significant increase in the deployment of powered devices (PDs) as there was no need to hire an electrician and a cabling specialist to deploy. Installers used Power over Ethernet networking solutions to provide power and data over a single cable to all manner of PDs.

802.3at (PoE+)

As time went on, device manufacturers created better solutions that required more power to operate. The 15.4 Watts that 802.3af provided was no longer acceptable, which led to a new Power over Ethernet standard. 802.3at was developed, providing up to 25.5 Watts of power to the PD. The increase in power was now able to support more intricate devices, such as cameras with movement motors and wireless access points with increased range.

After the 802.3at Power over Ethernet standard was introduced, organizations and device manufacturers were pushing the limits of technology. Quickly, there was a  need for even more power as devices became increasingly complex with additional features and mechanical capabilities. However, the industry and standards development was moving slower than the demand for better standards.

Users continually pushed the limits of existing technology and required additional power to support these systems and devices. We call this period the “wild-wild west” as six competing technologies looked to fill the void. Unfortunately, with no set standards to build upon, these separate technologies did not interoperate with one another.

802.3bt (PoE++)

Eventually, the industry developed the 802.3bt standard, also known as PoE++. An 802.3bt device delivers 60 Watts of power from the PSE (power sourcing equipment) to ensure 51 Watts to the PD. Industry adoption of 802.3bt was slow as several device manufacturers developed their own technologies during the “wild-wild west” period. Industry players are slowly moving towards the 802.bt standard as it is backward compatible with 802.af and 802.3at, but not all the competing standards developed during this time.