Dave Liquorice wrote:
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.
AFAICR the center pairs are Ethernet. 4/5 and 3/6. These must be pairs,
and must be wired pin to pin etc.
The outers are used for telephony in structured systems.
I have used all of them to get a serial signal around - Cisco routers
come with RJ45 serial consoles for example.