Here is a very interesting message on wiring a 100 Mb home network that I saw posted in a news group that I felt was so important I am posting a copy here. Notice how easy it is to degrade a 100 MB home network to a 10 Mb home network.
"You will certainly notice the difference between CAT-3 and CAT-5 cabling if
you try running the home network at 100Mb full duplex. If I remember
correctly, CAT-3 does not have the same number of twists per foot, which
means cross talk and noise is different. At 10Mb half duplex (one signal
pair only might be active) you probably don't notice it much, but at 100Mb
Full Duplex (both pairs have active signals) you would start having
problems. (Network switch assumed.)
100Mb in a home seems a little over kill, until you start considering all
the home automation that you can install doing it, including voice phone
over IP, video conferencing with relatives (via DSL or cable modem to
outside world), and network back ups of the installed machines.
When I installed the CAT-5 in my home, I certified the cabling with a Fluke
DSP4000, which tests for signal-to-noise, cross talk, impedance, etc. An
extra half inch to inch of untwisted cable is almost enough to fail the
CAT-5 certification. We tested a RJ-45 coupler that was NOT CAT-5
certified, it failed horribly, lots of cross talk, signal to noise did not
exist! The coupler was only about 1.5 inches long (total). When I took it
apart the pairs were not twisted together, just all running parallel in
side the coupler. The coupler would probably work fine for CAT-3, but when
I tried it on CAT-5, the NIC's all fell back to 10Mb half duplex!
I used "expensive" good CAT-5 cable bought from a networking supply store
and the Belden cable bought from Home Depot. When certifying, you could
not see any difference in the two. But we could certainly see problems
when I or my daughter got sloppy and untwisted too much cable."
--
Dennis Heidner |
