Comp and Communication Seminar 5 (1)

8/4/2019 Comp and Communication Seminar 5 (1)

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Communication and its

basic elements

Communication is the

process of transferring a messagefrom one point to another .

Following are basic elements• A sender (source) which creates

the message to be transmitted.• A medium that carries the

message.• A receiver (sink) which receives

the message.



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Data transmission

modes

• Simplex•

Half-duplex• Full-duplex



33

g

a anAnalog

Transmission DigitalTransmission • a digital signal take

discrete set of values.• A digital signal is a

sequence of voltagerepresented in binary form

Analog Transmission• In analog signal the

transmission power variesover a continuous rangewith respect to sound, light and radio waves.

• Analog signal is measured in volts and its frequency is

measured in hertz.



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Asynchronous and SynchronousTransmission

Asynchronous

Transmission • In asynchronous

transmissiondata istransmitted

character bycharacter asyou go ontyping on a

keyboard.

SynchronousTransmission

• In the

synchronous

mode the saveddata istransmittedblock by block.Each block cancontain many

characters.



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MAJOR COMMUNICATIONDEVICES

• Wire Pairs• Coaxial Cables• Microwave• CommunicationSatellite



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Network•

A computer network is a network of computers that are geographicallydistributed, but connected in a

manner to enable meaningfultransmission and exchange of dataamong them. Sharing of information and resources (bothhardware & software) is the mainobjective of a computer network.


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Types of network • Networks are mainly classified into three

types:-

1. LAN (Local-area

Network).2. MAN (Metropolitan-area

Network).3. WAN (Wide-area

Network).



LAN• It has a limited geographic coverage

of a 1-5 kilometers.• LAN typically provide communication

facilities within a building or a

campus.• Data transmission rates are usually

much higher.• The data transmission rates are

increasing continuously day by day.• It’s usually range from10 megabit per

second (mpbs) to 1gigabit per second

(gbps).



How LANWorks?

• Early LAN (Local Area Network)networks were formed using coaxial

cable• The basic application of this cable isto connect the radio transmitters with

their antennas.• Most common type of developing LAN(Local Area Network) network is the

Ethernet.



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ETHERNET•

- Ethernet is a 10Mbps LAN that usesthe Carrier Sense Multiple Access withCollision Detection (CSMA/CD)

protocol to control access network.: Fast Ethernet :FastEthernet supports amaximum data rate of

100 Mbps. It is sonamed becauseoriginal Ethernettechnology supported

only 10 Mbps.

Gigabit Ethernet: Gigabit Ethernet is an extension tothe family of Ethernet computer

networking and communicationstandards. The Gigabit Ethernetstandard supports a theoreticalmaximum data rate of 1 Gbps (1000Mbps).

http://compnetworking.about.com/library/glossary/bldef-ethernet.htm

http://compnetworking.about.com/library/glossary/bldef-kbps.htm

http://compnetworking.about.com/library/glossary/bldef-kbps.htm

http://compnetworking.about.com/library/glossary/bldef-ethernet.htm



1111

Some hardware

requirement for LANv Transmission channel.

v NIU (Network Interphase Unit).

v

Servers.v Workstations.



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MAN•

MAN is a large computernetwork that spans(extent) a metropolitanarea or campus.

•

Its geographic scope fallsbetween a WAN and LAN.

• A MAN optimized for alarger geographical area

than a LAN ranging fromseveral blocks of building

to entire city.



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WAN

• WAN may extend over several

thousands kilometer.• It can operate nationwide or it can

say even worldwide.•

Transmission rates in WAN usuallyrange from 1200bps to 2 mbps.• The data transmission rates are

increasing continuously with

advancements in technology.• Its cost may be very high because

transmission media used are leased

lines or public communicationt m h t l h n lin



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Some hardware requirementfor WAN

• Bridge = They are used to connect twoLANs together.

• Routers = they are used to connect both

the LAN & WAN. IN this Non-similar also beconnected.• Gateways = this is used to connected two

dissimilar LAN.



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What’s a protocol?

A l l a c t i v i t i e s i n t h e i n t e r n e t

t h a t i n v o l v e s t w o o r m o r e r e m o t e e n t i t i e s i s g o v e r n e d b y a p r o t o c o l . ( r o u t i n g p r o t o c o l , e t c . )



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COMMUNICATION PROTOCOL

PROTOCOL IS A

FORMAL DESCPRIPTION OF MESSAGE

FORMATS AND RULESTHAT TWO OR MOREMACHINES MUST

FOLLOW TOEXCHANGE THOSEMESSAGES.



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ROLE OFCOMMUNICATION

PROTOCOL• DATA SEQUENCING• DATA ROUTING• FLOW CONTROL•

ERROR CONTROL• PRECEDENCE AND ORDER OF

TRANSMISSION• CONNECTION TERMINATION AND

ESTABLISHMENT• DATA SECURITY



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Open Systems Interconnection (OSI) is a set of internationally recognized, non-proprietarystandards for networking and for operating

system involved in networking functions.

An open system is a set of protocols that allow twodifferent systems to communicate regardless of their

underlying architectureOSI reference model is a concept that describethe steps to be followed for data communicationto take place.

Creating a guideline for network datatransmiss ion between computer and componentsthat have different hardware vendors, software,operating systems and protocols



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Introducing the OSI Model

Open Systems

InterconnectionsModels

Th OSI R f M d l



2020

The OSI Reference Model

The OSI reference model consists of seven layers, not including layer 8, theend user’s application, and layer 0 the physical transmission media.

7. Application Layer

6. Presentation Layer

5. Session Layer

4. Transport Layer

3. Network Layer

2. Data Link Layer1. Physical Layer

8. O/S or User Application

0. Physical Transmission Media



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TC

P/IP

Transmission ControlProtocol (TCP)

Software that breaksmessages intopackets, hands themoff to the IP softwarefor delivery, and then

orders andreassembles thepackets at theirdestination

Internet Protocol (IP)

Software that dealswith the routing of

packets through the



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Difference between OSI andTCP/IP

OSI

Open System Interconnection

1. The OSI model is a referencemodel

2. In OSI model, the protocolscame after the model was

described.

3. The OSI model has 7 layers.

4. The OSI model supports bothconnectionless andconnection-oriented

communication in the networklayer, but only connection-oriented communication intransport

TCP/IPTransmission Control / Internet

Protocol

1. The TCP/IP model is animplementation of the OSImodel

2. In TCP/TP model, the protocolscame first, and the model wasreally just a description of theexisting protocols.

3. The TCP/IP model has only 4layers.

4. The TCP/IP model supportsboth connectionless andconnection-orientedcommunication in the transportlayer., giving users the choice.



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Comp and Communication Seminar 5 (1)

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