Bedtime Reading - Linux StepByStep

BEDTIME READING-UTP CABLING

Edited and bashed by Mike Andrew

UTP connections using RJ 8 pin connectors.

These connectors are not as straightforward as they should be. Your cabling can be wrong but work at 10Mb and not at 100Mb. The cause of the problem is the non-standard signal arrangement of the nic card.

The nic card

1	Transmit
2	Transmit Return
3	Recieve
4
5
6	Recieve reuturn
7
8

What you are seeing here is two twisted pair signals. One for recieve and one for transmit. The two separate signals allow for full duplex transmission. It is the full duplex ability of UTP that has caused RGB (coax) to lose favour.

But, the circuit designer had a bad weekend and made an serious error. The industry has paid ever since.

The Cable

1	White/Green
2	Green
3	White/Orange
4	Orange
5	White/Blue
6	Blue
7	White/Brown
8	Brown

There are four twisted pairs in this standard UTP cable.

The unwary immediately make 1:1 cables up as God intended.

It will fail because the ORANGE signal is NOT associated with it's correct pin 6.

It is quite likely you will get a connection at 10Mb, unlikely at 100.

So called 1:1 Cabling

1	White/Green	White/Green	1
2	Green	Green	2
3	White/Orange	White/Orange	3
4	Blue	Blue	4
5	White/Blue	White/Blue	5
6	Orange	Orange	6
7	White/Brown	White/Brown	7
8	Brown	Brown	8

Computer <-> Distibution box.

Computer <-> Computer cabling (Crossover)

1	White/Green	White/Orange	1
2	Green	Orange	2
3	White/Orange	White/Green	3
4	Blue	Blue	4
5	White/Blue	White/Blue	5
6	Orange	Green	6
7	White/Brown	White/Brown	7
8	Brown	Brown	8

remember the sequence:

Wherever you see "Green" above, substitute "Orange," and vice-versa.