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Power-over-Ethernet goes green

Posted: 02 Jun 2008 ?? ?Print Version ?Bookmark and Share

Keywords:Power-over-Ethernet? PoE systems? Energy Efficient Ethernet? WLAN? RJ45 connector?

PoE systems with new capabilities are being deployed against the backdrop of more stringent power requirements of the Energy Efficient Ethernet standard and other green initiatives. A number of key PoE technologies address this challenge to improve energy efficiency across the enterprise.

Here's how the efficiency of PoE systems compares to traditional wall adapters in various applications, and how new techniques and technologies, including dynamic power management and emergency power management, promise to make new PoE solutions more power- and cost-efficient.

Power and data have been bundled together on the same electrical cable since the late 1800s. However, the original Ethernet (IEEE 802.3) systems developed in the 1970s did not have provision for power. In the 1990s, during the arrival of data packet technology, alongside growing transmission rates and evolving VoIP, it became clear that Ethernet had to adapt to enable VoIP to be simple and reliable as traditional and digital telephony.

At the same time, WLAN protocols became sophisticated enough, with sufficient bandwidth, to replace wired Ethernet in some applications. Thus, strategic placement of WLAN access points, where AC power is not necessarily available, became a requirement. VoIP and WLAN technologies paved way for the IEEE 802.3 working group and the IEEE 802.3af task force, which developed specs to enable the transmission of data and packets on the same CAT class of Ethernet cable.

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