Security Technology Executive

JUL-AUG 2018

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ACCESS CONTROL TRENDS AND TECHNOLOGY 2018 S-19 S o what exactly is Power over Ethernet (PoE)? In the simplest terms, it is utilizing Ethernet cabling to carry not only data between devices, but also to carry the necessary electrical power. This solution has some obvious advantages when the cabling is often already in place. Since additional cabling doesn't need to be installed it is clearly cheaper. Right? That is usually the case but not always. Standards Typically, if a device states that it is "PoE compatible", this means that it adheres to the universal standard for PoE, which is IEEE 802.3af. It also means that it can be safely con- nected to other PoE compatible devices. So two devices connected across a network link, such as an Open Options NSC-100 receiving its power from a PoE network switch, becomes a PD (Powered Device), while the PoE network switch becomes known as PSE (Power Sourcing Equipment). Clearly, not everything connected to a network is designed to receive PoE. The stan- dard includes a process that checks to be sure that the equipment is compatible before "turning on the power". The PD has to display a signature that the PSE checks before enabling PoE to the port. This takes place within a very small amount of time, so wiring something up for PoE is as simple as just plugging it in. Ethernet cabling is used to carry not only data between devices but also to carry the necessary electrical power. Image Courtesy of BigStock.com By Roscoe Coffman

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