An industry-wide Power over Ethernet (PoE) standard was officially ratified in 2003 with IEEE 802.3af, and since then the use of PoE technology has rapidly grown.
Analysts estimate that by 2012 one quarter of all Ethernet ports will be PoE-capable. As knowledge of PoE's capabilities and benefits has spread, more and more system operators have taken advantage of PoE technology. However, the IEEE 802.3af standard has a few limitations that make it unsuitable for certain demanding applications. In response, the IEEE 802.3at standard, also known as PoE Plus, was ratified to further expand the scope and capabilities of standardized PoE devices. This white paper will identify the key additional advantages offered by PoE Plus and explore the enormous potential of this new technology in scenarios that previously could not take advantage of PoE.
PoE: A Brief History
Ethernet technology has been used for decades and Ethernet cables can now be found in enterprise offices, residential homes, and industrial automation. In most systems Ethernet cables already go nearly everywhere, so it would naturally be more efficient if these Ethernet cables could deliver both data and power. This would completely eliminate the need to find a local power supply for each of your devices, dramatically expanding device deployment flexibility and eliminating power cabling costs. The PoE idea was so promising that many vendors, such as Cisco, 3Com, and Intel, developed proprietary PoE technology. Users who adopted proprietary solutions were on the "bleeding edge" of technology—while they enjoyed the benefits of PoE technology, they also needed to deal with countless headaches such as interoperability and compatibility issues, vendor lock-in, and inconsistent support. The fact that these proprietary solutions were used at all, despite their many hazards, testifies to the fundamental usefulness of PoE technology.
Fortunately, in 1999 the IEEE began to work on a PoE standard, which was finalized in 2003 with IEEE 802.3at. With a standardized, documented, and widely available technology, PoE technology truly took off. PoE can supply power to devices in locations where it was previously difficult, if not impossible, to deliver power. Examples of such devices include remote network switches, security cameras, and outdoor WLAN access points.
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