[rescue] RJ-21

James james at jdfogg.com
Tue Jan 28 18:47:12 CST 2003

At 04:03 PM 1/28/2003 -0600, you wrote:
>I have a Cisco Catalyst 5000 with RJ-21 telco connectors. I also have 
>three 48port patch panels. So I picked up a couple RJ-21 - 25pr Copper 
>cables. Now I need to punch them down. But I don't know what wire goes where.
>The cable has 50 wires, ten sets of 5. Each set has a different color wire 
>(Blue, Purple, Orange, Grey, Brown, Yellow, Red, White, Black, Green ) and 
>each set has Orange, Brown, Grey, Blue, Green striped wires.
>Anyone known of a page that lists how I connect these to the back of my 
>patch panel?

Here is the colorcode.

W       BL

R       O

BK      G

Y       BR

V       SL

Keep it in the columns to understand it. The left column is the major 
color, the right is the minor color. The top of the major  column is the 
starting point. Take the first major and pair it with the 1st minor, then 
the 2nd minor, then the 3rd minor and so on till you hit W+SL. Then drop 
down to the second major and start over at the top of the minor column. 
When you get to R+SL drop down to the 3rd major and start at the top of the 
minor column again. When you get to V+SL you are at pair 25.

SO if we follow this,
W+BL is pair 1
W+O is pair 2
W+G is pair 3
W+BR is pair 4
W+SL is pair 5
R+BL is pair 6
R+O is pair 7
and so on.....

Some things you need to know..
BK = Black
V = Violet (the proper name, not purple)
BL = Blue
BR = Brown
SL = Silver (the proper name, not grey)

In each pair one wire is the TIP wire and one wire is the RING wire (T & 
R). Lets look at pair one (W+BL). The wire body will be white and the 
stripe will be blue (TIP). Its mate will have a blue body and a white 
stripe (RING). When the major color is the body its TIP. If the 
manufacturer uses solid color bodies white will be TIP and white with blue 
stripe will be RING. If the wire maker uses this method you must strip back 
about 6~12 inches of jacket and gently fan out the wires and observe the 
twisted pairs. If you aren't gentle they will untwist and make it hard to 

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