DATA COMMUNICATION AND NETWORK
is the process of transmission
the data and information over a communication channel between two computers
which can be several different things
Data communication System:
Data Communication System consists of all the Hardware and software included in the
data communication.
Key Data communications Terminology
Session: Communication Dialog
between network users or applications
Node:A network attached device.
Path:end-to-end route within a network.
Circuit: The Conduit over which data travels.
Protocol:
Set of rules that allow communication and
transmit data between two devices.
Transmission Media / Channel / Link
It is necessary to have a pathway
or the media to be transmitted data from one point to another. The term media means the device that transmits the voice or
the data form one point to another.
There are
two type of Media
·
Un-Guided Media
·
Guided Media
Unguided (Radiated) Media: -In unguided
media message is broadcast through the air such as infrared, microwave, or
satellite
Guided Media
In Guided media
the messages flow through the physical media i.e.
Cables
Coaxial cable has a copper core (inner conductor)
with an outer cylindrical shell for insulation.
Twisted Pair Cables
Twisted- pair wire is the most commonly used
wire. There are two types of twisted pair cable, shielded
and unshielded twisted pair. Shielded twisted pair (STP) cable consists
of pairs of insulated solid wire surrounded by a braided shielding.
Another type
of twisted pair is UnshieldedTwisted Pair (UTP) which is most frequently used
network cabling.
|
Type |
Use |
|
Category
1 |
Voice
Only (Telephone wire) |
|
Category
2 |
Data
to 4 Mbps (LocalTalk) |
|
Category
3 |
Data
to 10 Mbps (Ethernet) |
|
Category
4 |
Data
to 20 Mbps (16 Mbps Token Ring) |
|
Category
5 |
Data
to 100 Mbps (Fast Ethernet) |
|
Category
6 |
Data
to 1000 Mbps (Fast Ethernet) |
|
Category
7 |
Data
to 10 Gbps (Fast Ethernet) |
Fiber optics consists of thousands of very thin filaments of glass fibers which
can conduct lights pulse generated by laser at
transmission frequencies that approach the speed of
lights. Fiber optics has greater data transmission rate as well as the
great security interference tapping.
Unguided (Radiated) Media: -In unguided media message is broadcast through the
air such as infrared, microwave, or satellite
There are many
systems today using infra-red communications. This is usually a directional
infrared light signal transmitted into the air and received by nearby devices.
These are the
signals we think of as being radio, television,
but they are now being put to use in wireless Ethernet
and Bluetooth communications technologies.
|
|
Computer uses two types of
signals for data transmission are used Analog and
Digital.
Digital Signals
A digital
signal is a stream of “0s” and “1s” so this type of signals is
appropriate particularly for today computer.
Analog Signals
Analog signals uses variation in
a signals to convey information. It is particularly
useful for Wave data like sound waves. Our phone lines and speakers are the
Examples of Analog Signals.
Modem
Modem word derived from Modulation and
Demodulation. Modulation means conversion of Digital Signals into Analog
signals While Demodulation means conversion of Analog signals into Digital
signals.
Network
The connection
of more than two computers so that they can share data & resources like
printer, CD-ROM is called as a Network.
Network classification
Networks are
classified according to their geographical coverage and size. The two most
common network classifications are local area networks (LANs) and wide area
networks (WANs).
A Local Area Network (LAN) is a network that is cover the
small area. It is generally limited to a geographic area such as a writing lab, school, or building. On most LANs, cables are used to connect the network
interface cards (NIC) in each computer.
Wide Area Networks (WANs) connect larger geographic areas, Using a WAN, schools in Multan can
communicate with places like Karachi in a matter of minutes, without paying
enormous phone bills.
Comparison chart
LAN
|
WAN
|
|
|
Definition |
LAN (Local Area Network) is a
computer network covering a small geographic area, like a home, office,
school, or group of buildings. |
WAN (Wide Area Network) is a
computer network that covers a broad area (e.g., any network whose
communications links cross metropolitan, regional, or national boundaries
over a long distance). |
|
Stands For |
Local Area Network |
Wide Area Network |
|
Covers |
Local areas only (e.g., homes,
offices, schools) |
Large geographic areas (e.g.,
cities, states) |
|
Speed |
High
speed (1000 mbps) |
Less speed (150 mbps) |
|
Data transfer
rates |
LANs have a high data transfer rate. |
WANs have a lower data transfer rate compared to LANs. |
|
Example |
The network in an office building
can be a LAN |
The
Internet is a good example of a WAN |
|
Data
Transmission Error |
low data transmission errors |
More data transmission errors. |
|
Set-up costs |
it is not
very expensive. |
it is very
expensive.. |
|
Maintenance
costs |
LAN is easier to maintain at relatively low costs. |
Maintaining WAN is difficult
because of its wider geographical coverage and
higher maintenance costs. |
The physical arrangement of the
computers/devices in a network is called network topology.
It’s a simple
type of the Topologies A linear bus topology consists of a main cable. with a
terminator at each end. All nodes
(file server, workstations, and peripherals) are connected to the linear cable(Bus).
Ethernet
and Local Talk networks use a linear bus topology.
A ring network
is a topology of computer networks where each node is connected to two other
nodes, so as to create a ring.
In a ring topology each computer connected with the two other
computer
Star Topology
In this topology all node/computer are directly connected
with the central device that called hub or switch
Tree Topology
It is the
combination of the Bus and star topology. Nodes are connected with the
hub/switch and switches are connected with the Central main line Bus.
Mesh Topology
In this network
each device/computer directly connected with the other all devices/computer.
Message can b
send with different path.
A
registered jack (RJ) is a standardized physical network interface for a computer
network of Twisted Pair Cable.
(RJ) connector use in the computer network for Twisted Pair
Cable ends.
The Cable(UTP/STP)
UTP cables are
connected with RJ-45 connectors with the following colors codes:
T-568A Straight-Through
Ethernet Cable
The
T-568A standard is supposed to be used in new network
installations. Most off-the-shelf Ethernet cables are still of the T-568B
standard; however, it makes absolutely no functional difference in which you
choose.
RJ-45 Crossover
Ethernet Cable
A good way of
remembering how to wire a Crossover Ethernet cable is to wire one end using the
T-568A standard and the other end using the T-568B standard.
By
looking at a T-568A UTP Ethernet straight-thru cable and an Ethernet crossover
cable with a T-568B end, we see that the TX (transmitter) pins are connected to
the corresponding RX (receiver) pins, plus to plus and minus to minus. You can
also see that both the blue and brown wire pairs on pins 4, 5, 7, and 8 are not
used in either standard.
·
Network Interface Card
(Nic)
·
Hub/Repeater
·
Switch/Router
·
I-O Port & Wall Face
Plate
·
·
Wall Duct & Patch Cords
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