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Computer networks - Media Types

A Presentation on the different types of media used in the implimentation of computer networks

Ben Thain

on 27 November 2014

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Transcript of Computer networks - Media Types

Computer Networking
Different Connection Media Types

Lesson Objectives
Before we start, we have to understand networking cable Cat5/Cat5e/Cat6
These are the four different pairs
of wires we have to work with...
You will understand the different types of cabling used to connect devices to not only a computer network but also as an interconnect media.
You will understand the building diagram in the assignment 2 brief, what is expected of you and also how to structure the diagram.
You will know the wiring scheme of a Cat-5 cable, the roles of each wire, how they correspond to an RJ-45 socket plug and have the ability to make one from scratch
Firstly, lets start with the Cat 5 format (10/100 baseT) this can account for STP and UTP. There are several wires included inside the outer casing. There are 8 wires in total, 4 pairs. Green, Green Stripe. Orange, Orange Stripe. Blue, Blue Stripe. Brown, Brown Stripe.
Lets take a closer look at these wires...
As you can see, there are twists in the line. each of these twists are there to minimise the 'crosstalk' this is where the electrical current running through the cable chatters to the other wires slowing down data transmission.
Transmitting Pair (+ & -)
Receiving Pair (+ & -)
Redundant Pairs
This is the general make up of a standard
Cat5 Cable. Its construct allows for data
transfer of 100MB per second and the
longest the cable can be in any one section
for the line to still be running at optimum
performance is 100 meters.
Can anyone guess at the
benefits of upgrading to
Cat5e? or Cat6?
Hint: Only 4 wires are
currently being used
Hint: The frequency in a Cat5 cable
is 100Mhz
So where from here?
Now we know the basics of the Cat5 cable, lets take a look at the two typical types that I'm sure we've all heard of.
We have the Straight-Through (Standard) - Any ideas?
And we have a Cross over - Any Ideas?
Straight-Through Cable
A straight through cable is used when a device is being connected to a network via an interconnect device such as a hub, a switch or a router.

A Typical example of a straight-through or a 'standard connection cable' would be a patch cable. THis will be the short cable connecting your computer system here at college to the RJ-45 Plug in the Ethernet wall socket.
A Cross over connection on the
other hand...
A cross over connection is similar to the straight through with one (very obvious given the name) difference. The transmit and the receive wires cross over from one RJ-45 plug to the other

This connection is used for example when connecting two computer systems directly together with no interconnect devices.
(Unshielded Twisted Pair)
STP (Shielded Twisted Pair)
When working with any electronic device you are going to get electrostatic interference. This is referred to as electrical noise and can affect devices trying to transmit.
The typical sources of electrical noise are power lines, radar systems and generic electromagnetic signals. A solution to this was to twist the pairs of wires. The tighter the twist in the wire the better they were at resisting interference.
Depending on the application, budget of the job and need for the integrity of information to be retained, an option is to use STP. As you can see in the picture the pairs are twisted, though between the wires and the plastic jacket there is a secondary foil jacket (conducting shield). The benefits of this are that the signals are uninterrupted by interference and the data can travel at a faster speed.
The downsides to STP are, for starters, the science behind this type of cable is that the foil attracts the interference and disperses it through a grounding cable. If the cable is not grounded properly then its purpose is compromised drastically. The cable is physically bigger than UTP, and is more expensive (approx. £150 per 100m STP in comparison to £30 per 100m UTP) There is also an issue of STP being a little more fragile that UTP to.
UTP is unshielded cable. The twists are still the same (each pair is twisted together) It still has the same maximum optimum length of 100m, though there is no conducting shield or grounding line.
This plays a big role when dealing with interference. Obviously, this type of cable is more susceptible to electrostatic noise though was the common choice for home and small application. This would usually be the standard also due to the cost and style of network that it would usually be applied to.
Where is Networking Media technology going from here?
Since Cat5 we now have Cat5e and Cat6. The main benefit of these two types of cable is that is gives you a higher data bandwidth. 1000 instead of 100. This is referred to as a 'Gigabit' connection
In a Cat5e cable, they achieve this by using the two, currently redundant pairs of wires as secondary transmit and receive wires.
In a Cat6 cable, they are slightly larger due to the insulation that has to be used in order to subdue the extra 'chatter' or 'crosstalk' from the higher frequencies used in a Cat6 cable. If you consider a Cat5 or Cat5e works on 100Mhz then Cat6 works on 250Mhz. Higher data transfer rate, but more noise created...this incurs more cost also.
Lets take a look at the other types of cable used in Networking Solutions
< Coaxial Cable
Fiber Optic Cable >
Coaxial Cable
Coaxial cable has a single centre wire surrounded by an insulation shell which is grounded by a braided wire which acts as a shield. This shield works in the same way as the foil in an STP Ethernet cable.
The typical application of coaxial cable is the primary cabling used in the television industry though is also widely used for computer networks, chiefly, Ethernet. Although a lot more expensive to implement, it is a not less susceptible to electrostatic interference.
It is an older networking method and you would not see it too widely used in this day and age. You may see a coax Ethernet port on older networking cards
Fiber Optic Cable
Fiber optic cable is essentially several strands of optically pure glass that are capable of transmitting signal. There are two main basic cable designs, Loose Tube Cable (typically implemented in outdoor environments) and Tight Buffered Cable (typically used in buildings)
In fiber optic cable there are multiple tubes that run throughout (the coloured tubes pictured in the above images) these are called buffers. Each buffer typically holds up to 12 fibers and has a maximum count of over 200 fibers.
Loose-tube cable is usually armoured and shielded due to the nature of its application. Armouring (as shown in image one) is where there is steel armour wrapped around the jacket that contains the buffers there can also be double armour cable dependent on the application. There is also a gel filling compound is used to impede water penetration.

Tight-buffered cable is used for link or patch cable. This is for an internal application typically to link outside plant cables to terminal equipment.
So, what do we know?
You have each been given a task sheet. You need to identify as many parts of the cable medias as you can.

You also need to answer as many of the questions as you possibly can. Your answers will be checked after the quiz is over
Where does all this fit in?
This is all part of task 1 in assignment 2.

Remember: Single sentence answers will not be good enough for a pass. show off your knowledge!
So, Now we have looked at all the cables available on screen...
We are going to make our very own Cat5 straight-through and crossover cable!

We ARE going to test to see if they work...So no shortcuts!

Lets run this short clip and after, we will discuss...

Making our Cables
Any Questions about anything that you have seen or heard throughout this presentation?
Happy Days!
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