On 30 Sep 2003 18:11:05 GMT, wrote:

But it's *important* to use pairs between the right pins, or the
crosstalk/interference-rejection performance goes right out of the
window.
snip
*Functionally*, provided you pair consistently, the colours
you use, and which way round you do solid vs stripe, doesn't matter
at all: electrons are colour-blind.

But the pairs are physicaly located in a different place in the cable.
I suspect this could make a difference when really pushing the abilty
of the cable to carry the signal without to much degredation.

later
Checked the construction of a bit of CAT5, the pairs are arranged:

org
grn blu
brn

The wiring is:

T568A T568B
grn 1/2 org 1/2
org 3/6 grn 3/6
blu 4/5 blu 4/5
brn 7/8 brn 7/8

As can be seen the change in the org/grn wiring is not symetrical in
the cable, so a signal on the org pair is now physically closer to the
brn pair, like wise more separation greater for the grn/brn.

Now ethernet (10/100Mbps, not sure about Gigabit) only uses two pairs
the other two are not connected so it's probably not an issue with
ethernet but could be with other uses of CAT5.

--
Cheers
Dave. pam is missing e-mail