On Wed, Jul 09, 2003 at 01:17:36AM -0400, Robert Foxworth wrote:
>
>
> 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.
>
This is a _great_ description. I have a question, though. I'm not sure I
understand your pair designations. Based on your description, I assume
that the pairs are numbered this way:
Pins: 8 7 6 5 4 3 2 1
. . . . . . . .
Pairs: 4 4 2 1 1 2 3 3
Is that right? I know that RJ11 jacks number the first pair as the
inside wires and the outside wires as pair two. But is the above the way
pairs are numbered when 8 conductors are involved, regardless of what
type of wiring scheme is being used?
Paul
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