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[802.3af] specing polarity


I propose we tell designers to test their PSE and their PD both
to the 'Hot' - Opposite polarity and be done with this.
so here is the text:

The PSE must tolerate the application of a voltage of  equal and opposite polarity to its
own without incurring any damage  when such potentials are applied for an indefinite amount of time.


some vendors (chips and system) already have put together hardware
with opposite polarity to what we all agree to, and feel like we do not have
the right thing going here.

also for such a scenario to take place the following has to happen:

1- Both PSE's must fault (not discover before powering) or both be ' HOT '.
    we worked hard to insure this does not happen --in af.

2- We have a parallel diode that we specd (paid for) at the PSE end that takes care
   of  a hot-plug the current can return to the originating PSE.
   At the same time the diode helps a PSE discriminate by polluting anything in the other PSE
   that resembles a signature insuring no false discovery of another PSE.... No Hope here this
   better be reality or we are in bad shape.

3- Even with all PSEs following a single polarity  a cross over cable would take us back
    to the same problem again?!- if the PSEs are Hot - what am i missing.

That was my 2c for today,