Overview
Explains PoE and the supported powered devices.
Power over Ethernet (PoE) is a technology that allows Ethernet cables to carry electrical power, along with data, to powered devices. Power is supplied from the switch's power sourcing equipment (PSE) through the PoE-capable port and over the cable to the powered device.
If the powered device has mains power source (AC), the PoE-capable port provides redundant (backup) power. When the AC power becomes unavailable, a PoE-capable port detects and supplies power based on the power management mode.
Supported powered devices
PoE-capable switches can detect and supply power to devices that comply with universally adopted PoE standards and be IEEE standards-compliant. These device can be a Cisco device, such as a Cisco IP phone, or a third-party device. Third-party devices are classified based on the PoE standards they support. See Table for device classification based on PoE standards.
PoE technology is classified according to the IEEE standards that have evolved over the years.
Table shows the relationship between the PoE types, PoE standard, device types and the maximum power supported for each PoE classification.
| PoE types |
PoE standard |
Device type |
Maximum power supported |
|---|---|---|---|
| PoE (standard PoE) |
IEEE 802.3af |
Type 1 |
15.4 W |
| PoE+ |
IEEE 802.3at |
Type 2 |
30 W |
| PoE++ |
IEEE 802.3bt |
Type 3 |
60 W |
| 4PPoE |
IEEE 802.3bt |
Type 4 |
90 W |
| Cisco Universal Power Over Ethernet (UPOE) |
Cisco-proprietary technology |
Cisco devices |
60 W |
The Cisco UPOE is a Cisco proprietary technology and an enhancement to PoE. It allows a PoE-capable switch to provide 60 W (2 x 30 W) of power over standard Ethernet cabling infrastructure (Class D or better) by using both pairs of an RJ-45 cable-signal pair (wires 1,2,3,6) and spare pair (wires 4,5,7,8), and managing the power using Cisco Discovery Protocol (CDP) or Link Layer Discovery Protocol (LLDP).
Power classification refers to how a PoE-capable switch determines the power consumption class of a detected device. The classification is done based on the IEEE standards.
Table shows the relationship between the power consumption class and the maximum power level in each class.
| Class |
Maximum power level required from the device |
|---|---|
| 0 (unknown class status) |
15.4 W |
| 1 |
4 W |
| 2 |
7 W |
| 3 |
15.4 W |
| 4 |
30 W |
| 5 |
45 W |
| 6 |
60 W |
| 7 |
75 W |
| 8 |
90 W |