Ethernet Cables, UTP vs STP, Straight vs Crossover

Ethernet network cables that are used in local area networks are called twisted pair cables or ethernet cables. These are the Ethernet cables that are most used for computer to your router or modem, so you can have internet access.  One end of the cable plugs into your computer’s network interface card and the other end plugs into the network port of your router, switch, or modem, depending upon what you’re using.  

Now Ethernet twisted pair cables come in two different types. 

Unshielded Twisted Pair:

The first type is unshielded twisted pair (UTP), which is the most common type of cable that is used now a today. Unshielded twisted pair consists of four pairs of color-coded wires twisted around each other. The wires are twisted to prevent electromagnetic interference or crosstalk.  This type of network cable is what most people use in their home or business. And the second type is shielded twisted pair.

Shielded Twisted Pair:

Shielded twisted pair is very similar to unshielded twisted pair, except that it has a foil shield that covers the wires. And this shielding adds an extra layer of protection against electromagnetic interference leaking into and out of the cable. This type of cable is mainly used for industrial purposes and not so much in a home or business.

Typically, you would buy a bulk roll of twisted pair cable and then you would have to wire them correctly as per IEEE standard and then attach RJ45 connectors to both end. So to do this you would have to remove the protective sheathing at each end of a network cable to expose the wires.  And this is done by using a cable stripper.

Stripper

The cable is inserted into the cable stripper and then the outer sheathing is removed to expose the wires. And then you would insert the cable into a wire crimper to attach an RJ45 connector.  But before you touch the connector, the wires in the cable must be arranged in a certain standard. And that order will be different depending upon the purpose of the cable.

There are two type of cable standards we are using a day.  So for example the most common types of twisted pair cables that are used in a local area network, are straight and crossover cables. And these two cables have two different purposes.

Ethernet Cable Standards:

So, let’s talk about the wiring order that these twisted pair cables use.  And there are two different wiring standards that are used. One standard is called 568A and the other standard is 568B. And on the picture, you can see the wiring order for both the A and B standards. The orders are based on the color of the wires.  

For example, the 568A standard is wired in this order:  white green, green, white orange, blue, white blue, orange, white brown, and brown. And the 568B standard is wired in the following order: white orange, orange, white green, blue, white blue, green, white brown, and brown.

The only difference between the A and B standards is the green wires are swapped with the orange. And it doesn’t really matter which standard you use. Both standards do the same thing, but here in the U.S. most people use the B standard. Whether you choose the A or B wiring standard, if both ends of the cable are wired using the same standard then this is  known as a straight cable, which is known  as a patch cable. A straight cable allows signals to pass through from end to end. This is the most common type of cable that’s used in local area networks. A straight cable is used to connect computers to hubs, switches, routers, or modems, or in other words, it’s used to connect dissimilar devices together. As I said before this is by far the most common cable that’s used on local area networks. So, these two straight cables here do the exact same thing. The only difference is that one cable is wired using the A standard and the other one is wired using the B standard.

Let’s talk about a crossover cable. Now a crossover cable is also used on local area networks but it’s not as common as a straight cable. A crossover cable is created when both ends of the cable are wired using the two different standards. For example, one end is wired using the A standard and the other end is wired using the B standard. Crossover cables are used to connect two similar devices together. For example, crossover cables are used to connect two computers directly to each other without using a hub or switch and they can be also used to connect hubs to hubs, or switches to switches. So, they are used to connect two of the same devices together.