[Shop-talk] running ethernet wires

[Wayne]

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