Well over long runs if the cables internal twisted pairs have capacitor
mismatches between them then you get a non working network, but over the
couple of metres most use I'd imagine any old stuff would do.
I believe its driven at a fairly low impedance, or should be, to make it
more immune to issues like pick up or attenuation.

Most of the failures I've seen on bought leads have been poor plug
attachment or the actual connectors in the plug are crap.
Brian

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From the Sofa of Brian Gaff Reply address is active
"RJH" wrote in message
...
As if trying to sell people hugely expensive mains and audio cables wasn't
enough, it seems that computer cables are now fair game:

http://arstechnica.com/gadgets/2015/...no-difference/

(from comp.misc)

A vaguely interesting point is made in the test report however, referring
to cheap ethernet cable not meeting LAN spec. Quite what that means in
practice, I'm not sure.

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Cheers, Rob