Hello everyone, in this video we're going
to talk about Ethernet network cables that are used in local area networks and I'm
referring to twisted pair cables. These are the Ethernet cables that you'll find as you
connect your 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. The first type is unshielded twisted pair, which
is by far the most common type of cable that is used 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 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. So if you were the kind of person that is going to make their own
custom cables for your network, typically you would buy a bulk roll of twisted pair cable and then
you would have to wire them correctly and then attach RJ45 connectors to each 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. 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 have to be arranged in a certain order. And that order will be different depending
upon the purpose of the cable. 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. 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 screen you can see the wiring order for both the A and B standards. The
orders are based on the color of the wires. So 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. So 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. So 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 also 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. So 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. So 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. Now in addition to talking about the different types of twisted pair cables, we also
have to talk about the categories of twisted pair cables. And these categories are called CAT 3, CAT 5,
CAT 6, and CAT 7. And the difference between these is a maximum speed that they can handle without
having any crosstalk or interference. The numbers of these categories represent the tightness of
the twists that are applied to the wires. And as you can see on the illustration of the categories
and speeds of the different twisted pair cables So as you can see, the speed ranges from the lowest
category which is CAT 3 at 10 megabits per second and all the way up to CAT 6a and CAT 7 which has
speeds of 10 gigabits per second. Now most networks today would use at least CAT5e on their networks.
Because most networks would be running at least at gigabit speeds. So CAT 3 and CAT 5 are slower
than gigabit and are pretty much obsolete today. But of course if you're running a network that
can handle 10 gigabit speeds, you would have to use CAT 6a or CAT 7 on your network. But even if
you have an older network that's running slower speeds, you can still use CAT 7 because it is
backward compatible. CAT 7 is actually a shielded twisted pair version of CAT 6a. And finally
the latest version is CAT 8. Now CAT 8 is the ultimate copper cable. It's a shielded twisted pair
cable which has a delivery speed of 40 gigabits per second up to a distance of 30 meters,
which is 4 times faster than CAT 6a or CAT 7.
