[Shop-talk] running ethernet wires
Wayne
wmc_st at xxiii.com
Tue Apr 7 12:53:30 MDT 2009
Randall wrote:
> I'm pretty sure the same thing holds for B. Phones don't care about pairing
> nearly as much as Ethernet does; and the pairing is the only difference
> between 568A and 568B.
Correct. Both 568A & 568B, as applied to modular connector wiring, only
swap the 2nd & 3rd pairs (orange & green) around. Both configurations
are electrically identical, with "straight through" wiring. Analog
"POTS" phones only use the 1st blue pair and it's identically positioned
on both anyway. 568B is preferred.
On old wiring, like cat-3, the 4th brown pair was often lower quality
with hardly any twisting and was unsuitable for some data applications.
Half duplex 10Mb & 100Mb only use the 2nd and 3rd pair. Full duplex
100Mb & 1000Mb use all four pairs.
-Wayne
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