Data Communication Networks

•Introduction:–Communication of one form or another has always been a part of human existence.–Examples:

•Cave dwellers drew pictures to tell others about hunting trips.•Native Americans created smoke signals from fires as warnings about danger.•Pony express was used to deliver mail across America.

–Disadvantage of these methods in today’s world:•Not fast enough to keep up with the demands of the society.

Data Communications

Channel Company

EarthStation Earth

Station

Satellite

Cable Company

Consumer /Cable Channel Viewer

TELECOMMUNICATIONS

Greek Prefix: ‘Tele’ – Far offLatin: ‘Communicare’ – To Share

Data Communications

Computer

Computer

Modem

Modem

Telephone Lines

DATA COMMUNICATIONS

TELECOMMUNICATIONS

Data Communication Networks

•Data Communications:–Transmission of data,

•From point A (source) to point B (destination),•Usually computer to computer,•Over some type of medium (such as telephone line).

–Refers to the transmission of information mainly in,•Digital format or•Computer-readable form,•Over a communications network.

–It is a subset of Telecommunications,•Telecommunications is also concerned with,

–The transmission of audio, video and graphical data also in

»Analog format.

Data Communication Networks

•Networks:–It is a,

•Group of equipments (computers and related devices), •Connected by communications facilities through,

–Transmission lines or a wireless system,

•Over which users situated in many locations transfer information.

Advantages of Data Communication Networks

Non-Networked Office Environment

Networked Office Environment

Data Communication Networks•Data Communication Networks:

–Advantages of ‘Networked Office Environment’ over ‘Non-networked Office Environment’:

•Less manual work.–No need to retype the data again / No need to use removable drives to transfer information.–Chances of errors decrease.

•Easy access.–Can be accessible from anywhere, anytime.

•Resource sharing.–One resource can be easily shared with multiple computers.

•More efficient.–Time is saved.

•Fault tolerance.–No problem if one computer / machine goes down.

Data Communication NetworksBhuj Branch Office

LAN (Local Area Network)

Ahmedabad Branch Office

LAN (Local Area Network)

TelephoneCompany

Office

MAN(Metropolitan Area Network)

Data Communication NetworksBhuj (India) LAN Ahmedabad (India) LAN

TelephoneOffice

MAN

Texas (US) LAN California (US) LAN

TelephoneOffice

MAN

WAN (Wide Area Network) INTERNET

Components of Communication Systems

Source / Sender Destination / Receiver

Medium

Protocol / Language

Physical Components

Logical Component

Data Communication Networks•Components of a Communication System:

–Physical Components:•Sender / Source:

–Device that is sending the message.»Terminal, PC, Telephone etc.

•Medium:–Path the connects the source and receiver and is used to transmit the data.

»Copper cable, Fiber-optic cable, Airwaves etc.•Receiver / Destination:

–Device that accepts the message.»Terminal, PC, Telephone etc.

–Logical / Software Component:•Protocol:

–Set of rules that govern how two or more people or devices communicate.–Common language in which communication can take place.–Role of protocol is,

»To provide ‘Compatibility’ among systems.

Data Communication Networks•Applications of Data Communications:

–Due to the various advantages of ‘Data Communications’ / ‘Networks’,

•It is suitable for applications in various places / areas / industries.

–Networks are growing so rapidly that,•They are spreading in each and every aspect of daily life.

–Biggest application of Networks could be:•Very fast ‘people to people communication’ using some utilities such as:

–Email, Facebook, WhatsApp etc.

–List of all the applications of Networks would be endless.

•It is possible to get the applications of Networks in fields / areas,

–Ranging from A to Z.

Data Communication Networks•Applications of Data Communications / Networks:

–Airports / Airplanes:•Communications between flights in air and the ground is done using wireless networks.

–Banks:•Networks are used for all kinds of transactions.

–Colleges:•Extensively used in labs and libraries of colleges so that data can be easily accessed by the students / faculties.

–Diagnosis of Diseases:•Techniques such as ‘Endoscopy’ use Networks to diagnose various diseases.

–E-Commerce:•Most consumers are now moving to online shopping which is possible only due to Networks.•Other could be ‘Entertainment’.

–Factories:•Manufacturing machines co-ordinate with each other using a Network.

Data Communication Networks•Applications of Data Communications / Networks:

–Government:•Networks are used in many Government applications such as filing income tax returns, collection of taxes etc.

–Hotels / Hospitals:•Many facilities of Hotels/Hospitals work on Networks.

–Military:•To deploy troops (soldiers) in the war.•To find / locate targets from the fighter airplanes.

–Reservation:•Tickets (Hotels, Train, Flight) can be easily reserved from home using Networks.

–Space:•Used in space exploration by agencies such as ISRO and NASA.

–ISRO»Indian Space Research Organization

–NASA»National Aeronautical and Space Administration

•Other could be ‘Security’.