Configuring PoE

Only a device with a mark of PoE supports the PoE feature.

Overview

IEEE 802.3af-compliant power over Ethernet (PoE) enables a power sourcing equipment (PSE) to supply power to powered devices (PDs) through Ethernet interfaces over straight-through twisted pair cables. Examples of PDs include IP telephones, wireless APs, portable chargers, card readers, Web cameras, and data collectors. A PD can also use a different power source from the PSE at the same time for power redundancy.

As shown in Figure 488, a PoE system comprises the following elements:

•PoE power—The entire PoE system is powered by the PoE power.

•PSE—The PSE supplies power for PDs. A PSE can examine the Ethernet cables connected to PoE interfaces, search for PDs, classify them, and supply power to them. When detecting that a PD is removed, the PSE stops supplying power to the PD. A PSE can be built-in (Endpoint) or external (Midspan). A built-in PSE is integrated into a switch or router, and an external PSE is independent of a switch or router. The HP PSEs are built-in. Only one PSE is available on the device, so the entire device is considered as a PSE.

•PI—An Ethernet interface with the PoE capability is called PoE interface. A PoE interface can be an FE or GE interface.

•PD—A PD receives power from the PSE. You can also connect a PD to a redundant power source for reliability.

The PSE supplies power over category 3/5 twisted pair cable for a PoE interface in the following two modes:

•Over signal wires—The PSE uses data pairs (pins 1, 2 and 3, 6) to supply DC power to PDs.

•Over spare wires—The PSE uses spare pairs (pins 4, 5 and 7, 8) to supply DC power to PDs.

A PSE can supply power to a PD only when the selected power supply mode is supported by both the PSE and PD. If the PSE and PD support different power supply modes (for example, the PSE does not support power over spare wires, while the PD supports power over spare wires), you have to change the order of the lines in the twisted pair cable to supply power to the PD.

Figure 488 PoE system diagram

497