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Posted by Watson A.Name - \"Watt Sun, th on November 5, 2005, 1:44 am
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>
> > Are the signals on the two pairs polarity sensitive ?
>
>
> At least on 10 Base-T and 100Base-TX Ethernet system the
> parctical systems are not polarity sensitive. The Ethernet
> devices should be built in such way that they automatically
> correct the reversed polarity situation.
>
> > I never thought much
> > on this and I don't even know what the signals are. We are
troubleshooting a
> > network with lots of packet errors. The customer has not noticed any
> > degradation yet, but our monitor keeps going into alarm. Anyway, we
found
> > the green pair reversed, on the router to switch cable, but it must
have
> > been for some time, and the problem is recent. This has been
corrected,
> > cable tests out now. Not enough data yet to tell if that fixed it.
Just
> > wondering.
>
> Most propably your errors are caused by some other reason.
> --
> Tomi Engdahl (http://www.iki.fi/then/)
> Take a look at my electronics web links and documents at
> http://www.epanorama.net/
The ethernet signal goes thru a transformer on each end, and that
essentially makes the signal AC, eliminating any DC component. The
ethernet signals used in the original 10BaseT coax were manchester
encoded, which is not polarity sensitive, IIRC. I believe the signals
on cat5 balanced twisted pair are also manchester encoded. I will
crosspost to comp.dcom.cabling and for some other viewpoints.
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