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'[OT] Re: Network cat5 cabling question'
|"Paul B. Webster VK2BZC" <MIDCOAST.COM.AU> paulb
> I'm not actually sure what is meant by "cat 5". If it refers to
> shielded lines, no complaints at all. If it refers to 10BaseT cabling
> using 4 out of an 8-wire cable, then there is a trick as this is *not*
> in fact twisted pair.
If it is Category 5 Unshielded Twisted Pair (UTP), it most certainly does
consist of twisted pairs.
The silver satin flat modular line cord you are probably thinking of is
10BaseT networking requires twisted pair, but it doesn't have to be Cat 5.
I'm not sure what Category it officialy requires, but any normal twisted
pair telephone cable will work.
100BaseT requires Cat 5, although I've used it on short runs of Cat 3 and
I've seen lots of people try unsuccessfully to run 10BaseT or 100BaseT on
long runs of flat cable, and then test the cable with a cheap tester that
claims it's OK. The cheap testers only test continuity.
Note that flat modular telephone cable is often wired with a flip (i.e.,
pin 1 at one end is wired to pin 'n' at the other end. 10BaseT and 100BaseT
cable has to be "straight-through", unless you're using a crossover cable
between two nodes, in which case two pairs get swapped.
As long as we're off topic, I have a cat 5 cabling question:
Does shielded cat 5 wire work well for 10BaseT and 100BaseT?
Correction: someone wrote:
>10BaseT and 100BaseT cable has to be "straight-through", unless you're
using a >crossover cable between two nodes, in which case two pairs get
This correct but may lead you to wire it up wrong. Read the following so you
won't waste RJ45 connectors.
10BaseT and 100BaseTX are wired in a non-obvious pairing, with the first
pair using pins 1 and 2, but the second pair uses pins 3 and 6. The other
two pairs (pins 4,5) and pins 7,8 are usually present, but do not carry
signals in 10BaseT and 100BaseTX. They are usually used only in an
emergency as spares if the primary pairs are cut and the cable is
inacessable for replacement.
It is correct to say that the cable is "straight through", since each pin
at one end is connected to its same pin number at the other end. But do
not put the first pair on 1&2, second pair on 3&4, third pair on 5&6,
fourth pair on 7&8. If you go any distance with this pairing it won't work
or you get lots of errors. Hubs and network interface cards send and
receive using the pin 1&2, pin 3&6 pairing, respectively. The colors shown
below are widely used, but arbitrary as long as the pairing is respected.
RJ45 Plug PIN# RJ45 Plug PIN#
1st PAIR /-- 1 Orange/White 1 TxData +
\-- 2 Orange 2 TXData -
/-- 3 Green/White 3 RxData +
2nd PAIR / 4 -\ 3rd PAIR /Blue/White 4
\ 5 -/ \Blue 5
\-- 6 Green 6 RXData -
7 -\ 4th PAIR /Brown/White 7
8 -/ \Brown 8
(Looking at connector
end with the cable
running away from you)
| 87654321 |
Yes, category 5 cable (STP and UTP) is specified for 100BaseT
communications, and it is also good for 10BaseT, although you only need Cat3
You must be careful with grounding of the shield to prevent ground loops.
From: Nicholas Irias <VALUE.NET> cheapskate
To: MITVMA.MIT.EDU < PICLISTMITVMA.MIT.EDU> PICLIST
Date: Martes 12 de Mayo de 1998 9:37 PM
Subject: Re: [OT] Re: Network cat5 cabling question
>As long as we're off topic, I have a cat 5 cabling question:
>Does shielded cat 5 wire work well for 10BaseT and 100BaseT?
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