Cabling with RJ45 for LAN setup

Now a day’s normally we use 5e or 6 categories UTP cable for 10mb, 100mb or Gigabit LAN setup. The cable conductor can be both solid or strand. You should keep in mind that, they are RJ45 connectors in market which only support either solid or strand cable. There are also some connectors which support both types of cable. Both types of connector look like same. So you should be careful about this.

In a common LAN setup two types of cable connection needed. One is straight through cable and the other is crossed cable. Though the modern switch and Hubs can auto sense the cable connection type but you still need the old convention if your system use old instrument.

Straight and Cross connection

PC to PC cross connection

From the above picture it is clear when to use straight and when to cross. So crossed cable used for connecting switch / Hub to switch / hub or only single PC to single PC and straight cable used to connect switch to pc. In modern technology crossed is rarely used straight is used in everywhere (with modern switch and hub which have auto sense capability).

In cabling LAN the most important thing is to understanding the color code. In a UTP cable there are 4 pairs of cable with 8 different colors. These colors are not random and follow the standard color rules. There are two standards for numbering these color cables. They are as follow:

1.     TIA/EIA 568A 
2.    TIA/EIA 568B

Both standards have the same performance. Normally 568B wiring is popular for straight through cable.

TIA/EIA 568A standard

TIA/EIA 568B standard

From the picture you see two different numbering system of UTP cable.There are various standards for using LAN. Cabling connection is also varies according them. It also defines which type of cable we have to use. So you should have a little bit knowledge for better understanding what you are doing.

Some standards in its simple from are as follow:

1. 10base-T 2
2. 100base-TX
3. 100base-T4
4. 1000base-T 4
5. 10Gbase-T 4

There is a little bit more understanding needed to know the cabling scheme for different standard.We discus about common scheme for 10base-T and 100base-TX. Both standard use two pair of cable, one pair for transmitting and another for receiving. That's why the cable wiring of these two is similar and easy.

The numbering of RJ45 connector pin is also very important. Put the metallic part of the connector upside and face it to you then count from right to left 1,2,3,4,5,6,7,8.

Here is an example

RJ45 connector pin numbering

You know two types of cabling required for LAN setup. Straight cable is also some time defined as patch cable and the cross cable type. Again Remember do not use both numbering format, use any one of them, either 568A or 568B.For straight cable normally 568B numbering system followed. In this type on the both end of the cable same connection sequence used.

 

For 568B
Number of the cable	Cable Color	RJ45 Pin Number
1	white and orange	1
2	orange	2
3	white and green	3
4	blue	4
5	white and blue	5
6	green	6
7	white and brown	7
8	brown	8

 If 568A numbering system is followed then the connection will be as follow:

For 568A
Number of the cable	Cable Color	RJ45 Pin Number
1	white and green	1
2	green	2
3	white and orange	3
4	blue	4
5	white and blue	5
6	orange	6
7	white and brown	7
8	brown	8

568A straight Through

568B straight Through

Cross cable connections are used in single PC to PC connection or Hub to Hub connection. For connecting PC to hub straight cable connection is used. So don’t confuse yourself about this. Though modern Hub or switch can sense cable connection and straight cable connection can be used but there still some requirement to follow.

For cross cable connection on one end of the cable connect using 568A standard and on the other end connect using 568B connection.

One end of the cable  568A Other end of the cable 568B Connector pin Color code Connector pin Color code 1 white and green 1 white and orange 2 green 2 orange 3 white and orange 3 white and green 4 blue 4 blue 5 white and blue 5 white and blue 6 orange 6 green 7 white and brown 7 white and brown 8 brown 8 brown

 Here is the connecting procedure with RJ45

1.   Cut the cable according to your required measured length. Always cut some extra length in case of your emergency. Do not cut exact what you measured.
2.   Skin the cable at both end
3.  Untwist the cable
4. Place the wire according to your cable connection 568A or 568B.
5. Arrange them together close enough there were no gap among them.
6.  Cut them with a good cutter smoothly
7.  Insert them into connector carefully
8. With a good quality crimping tool attached them with RJ45
9.  For security check it with a cable tester. 

Now the cabling has done. But the LAN setup is not finished yet. Now you have to configure LAN in PC.
This article is for those who use 10base-T or 100base-TX standards. But if you use 100base-T4 or 1000base -T standards then the cross cable connection will be slightly different because they use all the four cable. The other things will be remain same. For this modified cross cable connection see the article The Crossover connections.