Power over Ethernet (PoE) Mode A vs. Mode B


Power sourcing equipment (PSE) may supply power to a powered device (PD) in one of two possible modes. (Note 1) The operating mode determines which two wire pairs carry the DC PoE current.

Mode A:
Pins 1 & 2 = DC+
Pins 3 & 6 = DC-
Mode B:
Pins 4 & 5 = DC+
Pins 7 & 8 = DC-

The implementation is fundamentally the same for 10/100Base-T and 1000Base-T systems. However, for 1000Base-T systems, there are always two wire pairs which carry both data and power simultaneously. For 10/100Base-T systems, it is possible to run power and data on separate wire pairs (Mode B).

Mode A is available upon special request only. Mode A

Mode B is standard for GlobTek’s 18W and 36W PoE products. Mode B

Note 1: PoE injectors >60W (for ex. GlobTek’s 70W GT-96600-7056) deliver power on all four pairs simultaneously, in a mode commonly called “4PPoE”.

GlobTek offers a wide variety of Power over Ethernet injectors utilizing patented technology which meets DOE EPS 2.0 Level VI compliant, a federal law in the United States, Canada, Europe, and other regions.


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