On 07/09/2013 06:46, Mike Tomlinson wrote:
En el artículo , John
Rumm escribió:

IME you need a fairly severe kink to actually cause a problem, and the
problem is usually loss of comms altogether rather than a reduction in
performance.

I'm afraid you're totally wrong.

I will make allowance since perhaps you have poor comprehension skills.

You will note that I said IME (that's "In My Experience"). Since I was
describing my experience, its not something you can dismiss as "wrong"
since its simply a recounting of fact.

I did not claim that a kink could not result in a performance reduction
and indeed if you actually thought about it before throwing your toys
out of the pram you would realise that a failure to work at all, is in
fact a significant drop in performance.

Obviously if you distort the physical geometry of a twisted pair then
you will introduce impedance discontinuities within the cable that will
cause signal reflections. It does not take many unwanted reflections to
knacker access on a CSMA/CD system, or to increase the frame error rate.
Twisted pair cable is far more resilient to the effects of kinking /
crushing etc than say co-ax, but its not immune.

Now this is an anecdotal sample of one, and I fully accept that its not
a statistically significant sample - it may be that I just don't meet
that many cables kinked in a way that causes non catastrophic
performance degradation. On almost all occasions I have encountered
problems resulting from cable damage, it has manifested in either
failure to communicate at all, or possibly a failure to operate in the
expected mode (i.e. gigabit / full duplex etc). Its possible that some
of the non critical failures will go unnoticed - since not all
environments will have managed switches able to report error rates, or
be tested with equipment able to perform that level of analysis.

Try googling the subject to find out
more from those who actually know what they are talking about.

Try to stop being such a prick, and we might pay more attention to you.



--
Cheers,

John.

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