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Re: fiber

At 03:19 PM 7/25/2000 -0600, Art Sackett wrote:
On Tue, Jul 25, 2000 at 05:43:00PM -0300, Gerard MacNeil wrote:
> I have read that you must ensure that the wires in the cat5 must be
> twisted all the way to the termination points to ensure reliabilty.

Except in unusually electromagnetically noisy environments, I've not
found any real support for this claim, although I've read it in more
than one place. It's been my experience that a few inches of parallel
conductors in a run of more than a few feet will cause no problems,
except in very noisy environments.

I have seen patchcords with a 3inch length stripped near the jack, and working on 10MBps. I have seen a patch panel, with the ENTIRE panel patched with 2' lengths of wire, nicely bundled and routed, though of course they had no twists with respect to each other any longer. And this guy, in 1995, had given a certificate that the network was "CAT-5 Certified" and "Future Proof". This was a AT&T vendor, with Krone certification as well.

I'm more concerned about observing the pairings so that the right
signal lines are paired, and have seen more noise-related problems as
a result of illogical pairings than short runs of parallel conductors.

I have rarely, and I do not use this word lightly, seen wire 3 & 6 twisted together. Practically all the cabling vendors I have seen patch a 1-2, 3-4, 5-6, 7-8 style. The network works, so they have been doing this for years, and they see no reason to change. This includes AT&T/IBM/AMP "specialists". Most installations are in offices, so the overdesign in the standard shield bad installations. And most vendors chant the "Structured Cabling" mantra, more often than not to push a Patch Panel in.

-- Ghane

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