Iīm not an expert in hardware design myself, Iīm just watching the discussion.
As I understand thereīre two groups:
group A prefers using spare pairs, to prevent existing investments into
expensive switches etc.
group B prefers phantom powering offering a pathb to 1000Base-T and giving
a chance for installations using only 2 pairs, saying group A requires
replacement of equipment.
I donīt understand the conflict. Theoreticly it should be possible to do
mid span phantom powering as well. This might require more effort in the
magnetics and eventually (but probably not) some signal conditioning. Or am
In production volume that should be still a cheap solution and AVOIDS the
need to replace existing switches/hubs etc., saves old installations in all
buildings and still gives a migration path to 1000 Base-T.
For new/replacement applications it could be integrated into the switch and
would not influence the BOM at all (except for a bigger power supply)