Chapter 2 : Network components.
Lecture 4
Network components:
- A computer network comprises the following
components:
1 - A minimum of at least 2 computers.
2 - A Network Interface Card (NIC) on each computer.
3 - Transmission media.
4 - Network interconnection devices (Repeater ,Hub,
Bridge, Router and Switch).
Network Interface Card(NIC):
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A Network Interface Card : is an expansion card that
enables a computer to connect to a network such as a
home network or the Internet using an Ethernet cable
with a RJ-45 connector.
- Also known as an Ethernet card and network adapter.
NIC provides the physical interface between
computer and cabling.
It prepares data, sends data, and controls the flow of
data. It can also receive and translate data into bytes
for the CPU to understand.
Transmission Media:
Definition :
- The medium through which the data is transferred from
one place to another is called Transmission Media.
- Networks are connected by some sort of wiring /cabling
or even wireless link that acts as a network transmission
medium that carries signals between computers.
Transmission Media:
The choice of the medium is very important since it affects:
• Network cost.
• Maximum operating speed.
Network media should be:
• High quality.
• Immune to noise.
• Easy to install and maintain.
Transmission Media:
Noise:
- Noise is unwanted electrical or
electromagnetic energy that
degrades the quality of signals
and data.
- Noise occurs in digital and
analog systems, and can affect
files and communications of all
types, including text, programs,
images and audio.
Transmission Media:
Different Types of Noise:
• Cross talk: is signal overflow from an adjacent wire.
• Attenuation: is the loss of signal strength that begins to
occur as the signal travels farther along the cable.
• Impulse Noise: Irregular pulses or spikes e.g. External
electromagnetic interference.
Transmission Media:
Types of transmission media:
1- Air (Wireless).
2- Magnetic Media.
3- Coaxial cable.
4- Twisted pair cable.
5- Fiber optic cable.
Transmission Media:
1- Air (Wireless):
The transmission of data is performed using radio waves,
infrared, or laser light.
The advantage of this medium is that it eliminates cabling.
The disadvantages are:
• Need of an unobstructed line-of-sight path between nodes.
• Data can be intercepted (jamming).
Transmission Media:
2- Magnetic Media:
- One of the most common ways to transport data from
one place to another is to write it on the magnetic tape
or floppy and physically transport it to the destination
machine physically.
Transmission Media:
3- Coaxial Cable:
Coaxial cable consists of a core of copper wire surrounded by
insulation, a braided metal shielding, and an outer cover.
Shape of the cable:
• The core of coaxial cable carries the electronic signals that
make up the data.
• Surrounding the core is a dielectric insulating layer that
separates it from the wire mesh.
• The wire mesh protects the core from electrical noise.
Transmission Media:
- At one time, coaxial cable was the most widely used
network cabling. There were a couple of reasons for
coaxial cable’s wide usage.
• It was relatively inexpensive
• It is light.
• It is flexible and Easy to work with.
Example:
Television cable is a form of coaxial cable.
Transmission Media:
Types of Coaxial cable:
There are two types of coaxial cable:
• Thinnet (10 Base 2) cable.
• Thicknet (10 Base 5) cable.
Transmission Media:
Coaxial-Cable Connection Hardware:
- Both thinnet and thicknet cable use a connection
component, known as a BNC connector, to make the
connections between the cable and the computers.
Transmission Media:
- There are several important components in the BNC
(British Naval Connector) family, including:
• BNC cable connector.
• BNC T connector.
• BNC barrel connector.
• BNC terminator.
Transmission Media:
4- Twisted pair cable :
- Twisted-pair cable consists of two or four insulated copper
wires twisted around each other.
• It is the most commonly and widely used in the network today.
• The twisting cancels out electrical noise from adjacent pairs and
from other sources.
• Twisted-pair cabling uses RJ-45 connectors to connect to the
computer. These are similar to RJ-11 telephone connectors.
Transmission Media:
Transmission Media:
The advantages of twisted-pair cable is that they are:
• Inexpensive.
• Easy to install.
Do not use twisted-pair cable if:
• You want to transmit data over long distance at high
speeds.
Transmission Media:
Types of Twisted-pair cable
There are two types of twisted pair:
• Shielded twisted-pair (STP)
• Unshielded twisted-pair (UTP)
Transmission Media:
Unshielded Twisted Pair (UTP):
• UTP cable consists to two or four insulated copper
wires.
• UTP is less resistant to noise but also less expensive.
Transmission Media:
CATEGORIES of UTP Cable:
Category 1:
This refers to traditional UTP telephone cable .
Category 2:
This category certifies UTP cable for data transmission up to 4
megabits per second (Mbps).
Category 3:
This category certifies UTP cable for data transmission up to 16
Mbps.
Transmission Media:
Category 4:
This category certifies UTP cable for data transmission up to 20
Mbps.
Category 5:
This category certifies UTP cable for data transmission up to 100
Mbps.
Category 5e:
Used in networks running at speeds up to 1000 Mbps (1 gigabit per
second [1Gbps]).
Transmission Media:
Shielded Twisted Pair (STP):
• STP cable uses a woven copper- braid jacket that is more
protective and of a higher quality than the jacket used by UTP.
• STP also uses a foil wrap around each of the wire pairs. This gives
STP excellent shielding to protect the transmitted data from
outside interference, which in turn allows it to support higher
transmission rates over longer distances than UTP.
Transmission Media:
5- Fiber optic Cable :
• Instead of using electrically (electric signals) to send data, fiber
optics cable uses light.
The advantages of fiber optic cable:
- It used to transmit data at very high speeds over long distances
in very secure media.
- Immunity to noise
Disadvantages of fiber optic cable:
- Expensive.
- Very hard to install.