On 20 May 2009 11:38:46 -0400, DJ Delorie wrote:


PeterD writes:
AFAIK, both are exactly the same electrically, only the polarity of
the wires (vis-a-vis color codes) is different. Were you to wire B to
B or A to A it is straight through. Wire A to B then it is a
cross-over.

Actually, not at all. Swapping green and orange swap whole pairs, not
swap wires within each pair.

I think the difference is in the number of twists per foot in the
green and orange pairs (orange has more).

Absolutely not. ALL pairs are ALL made EXACTLY the same.

If the TPF match the blue
or brown pairs, you get more crosstalk, so using the correct pairs may
result in less crosstalk.

No. Wiring it wrong gets you half duplex operation (sometimes) AND
un-terminated lines exhibiting the stray signals that end up getting
referred to as cross-talk.

http://www.networkclue.com/hardware/...rmination.aspx

Also how well the terminations are made matter too.

If you have more than say a half inch of untwisted wires exposed at the
ends when you terminate, it will fail GbE tests, and you will get 100
base T or less performance.

Terminations should also be of the metallic shielded variety, as
opposed to the old plastic plug and crimpers method.