[802.3af] Question Draft P802.3af/D4.2
I have a question on the following: Draft P802.3af/D4.2 Section 33.2.2 PI
pin assignments, Table 33-1-PSE pinout alternatives and associated text;
particularly sentences two and three in the paragraph immediately following
the table .
"Therefore, Alternative A matches the positive voltage to the TD pair. PSEs
that use automatically-configuring MDI/MDI-X ("Auto MDI-X") ports are
assigned the polarity
choice associated with MDI-X configurations."
Does this really mean that the positive voltage is ALWAYS on the TD pair?
Does this mean that non-automatic pair swapping ports (default MDI),
Alternative A (MDI), Table 33-1 column II, place the positive voltage as per
Table 33-1 column II AND ports that implement automatic pair swapping,
Alternative A (MDI_X or Auto-MDI-X), Table 33-1 column I, place the positive
voltage as per Table 33-1 column I independent of the TD pair? This could
occur if both the PD and PSE have automatic pair swapping ability. Positive
voltage assigned to pins 3,6 may be associated with RD or TD after LINK.
The third sentence of the paragraph would seem to contradict the second
sentence of the paragraph since 'Alternative A matches the positive voltage
to the TD pair' by definition.
I was not able to be part of this specific discussion at the DFW meeting. I
am hopeful someone can provide some help!
Thanks in advance,