Power over Ethernet (POE)

Power over Ethernet (PoE) is a technology that lets network cables carry electrical power. It allows IP telephones, wireless LAN Access Points, Security network cameras and other IP-based terminals to receive power, in parallel to data, over the existing CAT-5 Ethernet infrastructure without the need to make any modifications in it. PoE integrates data and power on the same wires; it keeps the structured cabling safe and does not interfere with concurrent network operation.

A typical PoE system consists of Power sourcing equipment (PSE) and a powered device (PD). The PSE may either be an Endspan (L2 Ethernet switch supporting PoE) or a Midspan (PoE hub). The PD is a PoE-enabled terminal such as an IP phone, Wireless LAN access point, etc. PSE provides the power on the cable for the PD.

The IEEE 802.3af, also called Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI), is the first international standard to define the transmission of power over Ethernet infrastructure. This standard specifies the protocol for delivery of a nominal 48 Vdc over unshielded twisted-pair cables (such as CAT-5), eliminating the need for a local power source for the remote device. It consumes less than 13 watts of power.

The PoE facility was developed to reduce the cost of network planning, cabling and installation. PoE saves time and money by avoiding the need for separate installation of Data and Power infrastructures. PoE makes network planning flexible and independent of switch cabinets and power sources, and also saves additional outlay for power and telephone networks (VoIP).