PoE Standards-based
PoE delivers DC electrical power over Ethernet cables to connected network devices. Standards-based PoE, sometimes referred to as "Active" PoE follows various IEEE standards used by multiple vendors.
There are multiple standardized PoE types which deliver varying levels of power in different ways. These types are based on IEEE standards.
- Type 1 - IEEE 802.3af
- Type 2 - 802.3at
- Type 3 and 4 - 802.3bt
There are also different PoE classes that range from class 0 to class 8. These define how much power should be sent to a device, ranging from 4 to 99 watts.
- Type 1 specifies four classes
- Type 2 specifies a single class
- Types 3 and 4 specify an additional four classes
Standardized PoE involves an initial negotiation between the powered device (PD), say an IP phone, and the power sourcing equipment (PSE), such as a PoE switch. The PD requests specific PoE requirements, and if the PSE supports those requirements, it delivers the requested power.
Standards-based PoE guarantees operation at up to 100 meters of CAT5 or CAT6 cable, the same distance that Ethernet is certified to function.
For non-standardized PoE, take a look at Passive PoE
Links:
https://networklessons.com/cisco/ccna-200-301/power-over-ethernet-poe