Here is the T-568B wiring spec, recommended for network
wiring (not telco wiring which is where -A or USOC is used)
The only difference is that the wire-pin assignment for
pairs 2 and 3 are reversed. If you are consistent, it makes
no electrical difference. The info below was done with
monospaced courier and tabs, btw.
Straight through: same format at BOTH ends:
Pin# Pair# Function Wire Color
1 2 Tx+ white/orange
2 2 Tx- orange
3 3 Rx+ white/green
4 1 --- blue
5 1 --- white/blue
6 3 Rx- green
7 4 --- white/brown
8 4 --- brown
As you see, only pairs 2 and 3 conduct signal.
Pairs 1 and 4 are electrically idle, but the spec
says they are all connected. When making cables you
need to connect them anyway to maintain proper
wire position.
To make a crossover cable, pairs 2 and 3 are
reversed at ONE end. Use the above format at
the first end, and use T-568A at the second,
as below:
pin# pair# function wire color
1 3 Tx white/green
2 3 Tx green
3 2 Rx white/orange
4 1 --- blue
5 1 --- white/blue
6 2 Rx orange
7 4 --- white/brown
8 4 --- brown
When looking into the mouth of the RJ45 jack,
with the contact wires up and the lock tab
down, pin 1 is on the (your) left.
When looking at the modular plug, with the 8
molded contact wires facing up, and closest
to you, and the lock tab on the bottom and facing
away from you, pin 1 is on your right.
You must maintain the wire twist as close to the
entry to the plug as possible. It helps to expose
about 2 inches of wire, lay them flat and together
in the proper sequence, pull them tight with needle
nose pliers, flex them while holding the ends with
the pliers so all the random kinkiness in the wire
is evened out, them cut the ends with __shearing
cutters__ (NOT nippers which will cause deformation
of the sheared ends leading to possible adjacent-
wire shorts) so that maybe a bit less than 3/4 inch
of the 8 wires are showing, so that when the bundle
is slipped into the mod plug, the wires stay in the
proper sequence and the twist is kept as close to
the ends as possible, and the wire anchor in the
mod plug gets a good bite into the jacket when the
crimp is done.
If you use solid wire, an AMP tool, and AMP plugs
made for solid wire, you will get consistent good
crimps. I personally found stranded wire hard
enough to work with, that maintaining proper
wire position was a hassle, I suppose there are
jigs that can be used for stranded, but I don't have any.
If you make a decent crimp you can use solid wire
everywhere and it will behave well. Spend the $
and get the proper tools. (my opinion)
(source: Cisco network academy lab companion/
workbook)
Bob Foxworth
----- Original Message -----
From: "Greg Schmidt" <slugmail@gschmidt.net>
To: <slug@nks.net>
Sent: Tuesday, July 08, 2003 18:18
Subject: Re: [SLUG] brighthouse
> steve wrote:
> >
> > When you crimp RJ45 plugs/jacks use the B color scheme. A is seldom
used,
> > this way you remain standard.
>
> Is B the one that has the orange pair on the left if you hold the jack
> with your thumb on top and your index finger against the clicky thingy?
> I couldn't dig up these standards in google. Anyone have a good link?
>
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