[TriLUG] OT: Home Depot and Cat 5
Aaron S. Joyner
aaron at joyner.ws
Tue Oct 5 12:51:56 EDT 2004
Brian Henning wrote:
>>One thing I can tell you is that the non-working cable has only 4
>>crimped. For long cables, should all 8 be crimped?
>As I understand it, 10-base-T needs 4 conductors (two signal, two ground)
>and 100-base-T requires all 8 (four signal, four ground).
>Someone correct me if I'm wrong!
Okay, you're wrong. :) 10MBit Ethernet and 100MBit Ethernet both only
use 4 conductors (2 pair) for signaling. Gigabit Ethernet, on the other
hand, does use all 8 conductors (4 pair) to do signaling. It's truly a
different beast from 10/100 Ethernet, although all Gig-E controllers
that I'm aware of also have the ability to signal via the older 10/100
method on only the 4 conductors.
I'm going to toss in a bit more of a rant about 568B color code and
punching down all of the conductors here that I somehow neglected to
include in my other post to this thread a moment ago. The two big
reasons for punching down all of the wires are future compatibility with
later standards like Gig-E, and the fact that those other pairs (because
they are also twisted with the signal-carrying pairs) can be grounded
and serve as "shielding" (note shielding is in quotes because it doesn't
work like traditional shielding, but it has a similar net effect).
Granted, most cheap equipment these days doesn't actually ground the
extra pins on the connectors, but (in my opinion) it's best to ensure
that you're cabling isn't the limiting factor in something not working
Aaron S. Joyner
More information about the TriLUG