Advanced data communications with its basic introduction

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1. Computer Networking
Introduction
Dereje M.

2. Overview
• Concept of Data Communication
• Communication Model
• Computer Networking
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3. Concept of Data Communication
• Data communications:
– Deals with the transmission of signals in a reliable and efficient
manner
– The exchange of data between two devices via some form of
transmission medium such as wire cable, wireless.
• An effective data communication system depends on the
following fundamental characteristics:
– Delivery:- the system must deliver data to the correct destination
– Accuracy:- the system must deliver the data accurately (no
alteration)
– Timeliness:- the system must deliver the data in a timely manner
– Jitter:-jitter refers to the variation in the packet arrival time. It is
the uneven delay in the delivery of audio or video packets.
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4. Data Communication Model
• The fundamental purpose of a communications system
is the exchange of data between two parties
• General block diagram of a simple communication
model
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5. Cont’d…
• The key elements of the communication model are:
– Source:- generates the data to be transmitted
• Telephones, PCs
– Transmitter:- transforms and encodes the information in
such a way as to produce electromagnetic signals that can
be transmitted across some sort of transmission system.
• Modem:- transforms digital bit stream into analog signal that
is suitable for the transmission media being used
– Transmission system:- this is either a single transmission
line or a complex network connecting source and
destination
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6. Cont’d…
– Receiver: The receiver accepts the signal from the
transmission system and converts it into a form that can be
handled by the destination device.
• For example, a modem will accept an analog signal coming
from a network or transmission line and convert it into a
digital bit stream
– Destination: Takes the incoming data from the receiver.
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7. What is Computer Networking?
• Networking deals with the technology and
architecture of the communications networks used to
interconnect communicating devices
• An interconnection of computers and computing
equipment using either wires or radio waves over
small or large geographic areas
– Two computers are said to be interconnected if they are
able to exchange information
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8. Why do we need Networking?
• Business applications
– Resource sharing: the goal is to make all programs,
equipment, and especially data available to anyone on the
network without regard to the physical location of the
resource and the user.
• Sharing common printer, data/information sharing
– Provide a powerful communication medium among
employees.
• email, videoconferencing and others
– Help companies in doing business electronically with other
companies, especially suppliers and customers.
• online booking, order online
– It is called e-commerce (electronic commerce)
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9. Cont’d…
• The client and server machines connected by a
network
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10. Cont’d…
• Home Applications
– Some of the more popular uses of networking (Internet) for home
users are as follows:
• Access to remote information.
• Person-to-person communication.
• Interactive entertainment.
• Electronic commerce.
• Mobile Users
– Portable office: some one can do activities that he/she is supposed
to do from office while walking or driving using portable electronic
equipment
• Example: to send and receive telephone calls, faxes, and electronic
mail, surf the Web, access remote files, and log on to remote machines.
• Social Issues
– Exchange messages with like-minded individuals.
• Example: politics, religion, sport, teaching/learning… etc
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11. Example
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