How many PoE ports are supported, what is the power budget for the entire switch and for each port in the ZyXEL Ethernet switches?
Power over Ethernet, or PoE, is a technology that allows electrical energy to be transmitted to a remote device along with data through a standard twisted-pair cable on an Ethernet network. This technology is intended for IP-telephony, access points of wireless networks, IP-cameras, network hubs and other devices to which it is undesirable or impossible to conduct a separate electric cable.
ZyXEL devices support PoE technology in accordance with IEEE 802.3af and IEEE 802.3at.
According to the IEEE 802.3af standard, direct current is provided with a nominal voltage of 48 V (min = 36 V, max = 57 V) through two pairs of conductors in a four-pair cable, with a maximum current of 400 mA to provide a maximum power of 15, 4 W.
The IEEE 802.3at standard (also called PoE +, PoE Plus or High PoE) provides for an increase in power supply (up to 30 W) and best classification methods. In this standard, a new mechanism for the mutual determination (classification) of devices was developed. It allows the power supply (PSE) and the powered (PD) devices to mutually determine each other when establishing a connection. 802.3at PSE devices can provide the required power to both 802.3.af standard PD devices and 802.3at enabled PD devices. Also, 802.3.at PD devices are able to determine when connected whether there is a power level necessary for them.
One of the most important features of the PoE Plus standard is to increase the maximum current to 600 mA to provide maximum power up to 30 watts.