Introduction
Power-over-Ethernet (PoE) eliminates the need to run power to other devices on a wired LAN. Using Power-over-Ethernet systems installers needs to run only a single Category 5 Ethernet cable that carries both power and data to each device. This allows for greater flexibility in the location of network devices and significantly decreasing installation costs in many cases.
There are two system components in PoE—the Power Sourcing Equipment (PSE) initiates the connection to the second component, and the Powered Device (PD). The current is transmitted over two of the four twisted pairs of wires in a Category-5 cable.
Power over Ethernet follows the IEEE 802.3af and is completely compatible with existing Ethernet switches and networked devices. Because the Power Sourcing Equipment (PSE) tests whether a networked device is PoE-capable, power is never transmitted unless a Powered Device is at other end of the cable. It also continues to monitor the channel. If the Powered Device does not draw a minimum current, because it has been unplugged or physically turned off, the PSE shuts down the power to that port. Optionally, the standard permits Powered Devices to signal to the PSEs exactly how much power they need.
The 8 10/100TX + 2 Gigabit copper/Mini-GBIC Combo with 8 PoE Injectors Managed Switch and the 8 10/100TX + 1 10/100/1000T/100/1000 SFP Combo with 4 PoE Injectors Managed Switch are the multi-port switches that can be used to build high-performance switched workgroup networks. Both switches are a store-and-forward device that offers low latency for high-speed networking. It also features a “store-and-forward “switching scheme. This allows the switch to auto-learn and store source address in an 8K-entry MAC address table. The switch is targeted at workgroup, department or backbone computing environment.
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