[Tfug] Yet another poser

jblais joe.blais at pti-instruments.com
Thu Sep 20 12:48:27 MST 2007



> -----Original Message-----
> From: tfug-bounces at tfug.org [mailto:tfug-bounces at tfug.org]On Behalf Of
> johngalt1
> Sent: Thursday, September 20, 2007 12:19 PM
> To: Tucson Free Unix Group
> Subject: Re: [Tfug] Yet another poser
>
>
>
> On Gigabit copper, all four pairs are swapped on a crossover cable.
> http://pinouts.ru/NetworkCables/1Gbcrossover.shtml
>
> linked from:
> http://en.wikipedia.org/wiki/Gigabit_Ethernet
>

I wonder if gigabit is just using double pairs in order to increase
current/reliability, or if it is splitting the signal somehow?  Kind of like
having 2 serial loops in parallel?  Could this kind of wire could mess up a
POE device?


>
>
> By the way, I strongly disagree with
http://www.alatec.com/info/other.html
where it says:

USOC RJ45 standard is not as widely used, but is an acceptable standard for
wiring ethernet.

If you used this, send and receive conductors would not be paired as they
should

--
If both ends are the same, I think the signals are still paired just because
it's straight through, but the twisting of pairs within the cable, for
inductance and other junk, may be different.  It would probably "work" but
perhaps not over as long a distance or it may get interference from nearby
power lines.  For something other than Ethernet, it may be a good thing.
RJ45 is probably older than this type of network wiring.  Remember those big
20-some-odd pin connectors for ethernet? the coax? the thin-net?





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