COMPUTER TECHNOLOGY
COMPUTER
NETWORKS
·
A computer network, often simply referred
to as a network, is a collection of computers and other hardware components
interconnected by communication channels that allow sharing of resources and
information. Simply, more than one computer interconnected through a
communication medium for information interchange is called a computer network.
TYPE OF COMPUTER
NETWORK.
LOCAL AREA NETWORK :
•Network
that connects computers and devices in a limited geographical area such as
home, school computer laboratory and office building.
METROPOLITAN AREA NETWORK :
•High
speed area network that connects local area networks in a metropolitan area
such as city or town.
WIDE AREA NETWORK:
•Networks
that covers a large geographical area such as country or the world.
Type of Network Architecture.
Client/Server :
- One computer acts as a sever tat provides services and the other computers (client) on teh network request services from the services from the server.
-A server is a computer that control access to the hardware, software and other resources on the networks and provides a centralized storage area for program. there are many type of server such as mail server, web server, file server and ftp server.
-A client is a computer that requests services from a server computer.
-Client/server networks are typically used when there is a constant need to access large files and applications or when multiple users want to share peripherals.
Peer-to Peer:
Network that typically connects fewer than 10 computers. All computers in the network have equal capabilities to use the resources (hardware, software, data and files) available on the network. With peer-to peer, there is no central server.
THREE TYPES OF NETWORK TOPOLOGY.
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Topology
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Explanation
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|
Ring
topology
|
·
A cable forms a closed loop(ring) with all
computers and devices arranged along the ring.
·
Data transmitted on the ring networks travels
from device around the entire ring, in one direction.
·
The ring topology primarily is used for LANs,
but also is used in WANs.
|
|
Bus
topology
|
·
A bus network comsists of a single central
cable, to which all computers and other devices connect.
·
Data, instructions, and informations is
transmitted in both directions.
·
Bus networks are popular on LANs because they
are inexpensive and easy to install.
|
|
Star
topology
|
·
All of the computers and devices (node) on the
network connet to central device, thus forming a star.
·
The central devices that provides a common
connection point fro nodes on the network is called the hub.
·
All data that transfer from one node to
another passes through the hub in one direction.
|
|
Topology
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Bus
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Ring
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Star
|
|
Diagrams
|
 |
 |
 |
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Central Device
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Not available
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Not availabe
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Hub or Switch
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Data Transmitted
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Both direction
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One direction
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Both direction
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Installation and Maintenance
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Easy
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Difficult
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Easy
|
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If one node fails
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Does not effects the rest of the nodes.
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The entire network stop
working.
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Does not effects the rest of nodes.
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WIRED COMMUNICATION MEDIA
- Wired communication refers to the data over the wire-based communication technology. Also waveguide (electromagnetism), used for high-power applications, is considered as wired line.
Alternatively, communication technologies that don't rely on wires to transmit data are considered wireless.
TYPE OF WIRED COMMUNICATION MEDIA
a)
Twisted
Pair Cable.
·
Twisted pair cable consists of two strands of insulated copper wire,
twisted around each other. This
twisted pair configuration some-what
reduces interference from electrical field.
·
Data is transmit through electric signal.
b)
Coaxial Cable.
·
Coaxial cable, or coax, has an inner conductor surrounded by a
flexible, tubular insulating layer, surrounded by a tubular conducting shield.
·
Coaxial cable differs from other shield cable used for carrying
lower-frequency signals, such as audio signals.
c)
Fibre Optic.
·
Method of transmitting information from one place to another by
sending pulses of light through an optical fibre. The light forms an
electromagnetic carrier wave that is modulated to carry information.
WIRELESS COMMUNICATION MEDIA
Wireless telecommunications is the transfer of information between two
or more points that are not physically connected. Distances can be short, such
as a few metres for television remote control, or as far as thousands or even
millions of kilometres for deep-space radio communications. It encompasses
various types of fixed, mobile, and portable.
TYPE OF WIRELESS COMMUNICATION MEDIA
a)
Infrared.
·
Infrared(IR) short-range communication, for example from consumer IR
devices such as remote controls or via Infrared Data Association(IrDA).
·
Infrared devices often must be within about 5 meters.
b)
Radio Wave.
·
Bluetooth technology uses
short-range radio wave to transmit data between two Bluetooth devices. To
communicate each other, Bluetooth devices often must be within about 10 meters.
·
WiFi (Wireless
Fidelity) transfer
data between devices at rate of 11-54 Mbps. To communicate each other, WiFi
devices often must be within about 30 meters.
c)
Satellite.
·
Satellite is a space station that receives microwave signals from an
earth-based station, amplifies the signals, and broadcasts the signal back over
a wide area to any number of earth-based stations.
COMMUNICATION PROTOCOL
A communications protocol is a system of digital message formats and
rules for exchanging those messages in or between computing systems and in
telecommunications. A protocol may have a formal description.
TCP/IP is short for Transmission Control Protocol/Internet Protocol.
TCP/IP is a network standard, specially a protocol, that defines how messages
are routed from one end of a network to the other, ensures the data arrives
correctly.
FDDI is a Fiber Distributed Data Interface (FDDI) is a network protocol
that is used primarily to interconnect two or more local area
networks, often over large distances. The access method used by FDDI
involves token-passing. FDDI uses a dual ring physical topology.
Transmission normally occurs on one of the rings; however, if a
break occurs, the system keeps information moving by automatically
using portions of the second ring to create a new complete ring.
.
REFERENCES
ü Books
·
SCORE A INFORMATION AND COMMUNICATION
TECHNOLOGY by Ismail bin Shaari.
ü Websites
