This article explains how to power up more PoE devices (PDs), what's the difference between 802. 3at mode as well as the difference between classification and consumption mode in Power over ethernet on your switch . PoE: Power over Ethernet (PoE) is a technology that allows Ethernet cables to carry electrical power, along with data, to powered devices. The initial allocation for Class 0, Class 3, and Class 4 powered devices is 15. This allows a single cable to provide both a data connection and enough electricity to power networked devices such as wireless access points. When working with your network devices, it's important to understand each device's power requirements and the types of Power over Ethernet (PoE) they support. Power is passed from Power Sourcing Equipment (PSE) over the twisted pairs to Powered Devices (PD) such as IP phones, IP cameras, card.