I'm reading about PoE and I wonder why there are 2 alternatives (A and B) to implement a PSE. Which are the benefits and drawbacks of each of them?
I am designing an end-span Ethernet switch with PoE (PSE) and I don't know which alternative is better. The IEEE 802.3af allows a PSE to use either of the two alternatives, but not working simultaneously. So, products the like in the market, which alternative do they implement?
It is cheaper to implement arternative B because you don't need a special transformer. So, what's the point in using alternative A?