OSI MODEL CONCEPT

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DURJOY SEN MAITRAROLL NO – 11G4MMS040

MSC (COMPUTER SCIENCE)3RD SEMISTER

BARRACKPORE RASTRAGURU SURENDRANATH COLLEGE

2

WHY WE NEED A NETWORK MODELTASK INVOLVED IN SENDING A

LETTEROSI MODEL INTRODUCTION

OVERVIEW OF OSI MODELPEER-TO-PEER PROCESS

DESCRIPTION OF OSI MODELAPPLICATION LAYER

PRESENTATION LAYERSESSION LAYER

TRANSPORT LAYERNETWORK LAYERDATA LINK LAYERPHYSICAL LAYER

CONCLUSIONREFERENCES

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WHY WE NEED A NETWORK MODEL ?

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TASKS INVOLVED IN SENDING LETTER

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THE OSI MODEL

NETWORK LAYER

DATA LINK LAYER

PHYSICAL LAYER

TRANSPORT LAYER

SESSION LAYER

PRESENTATION LAYER

APPLICATION LAYER

User support layers

Network support layers

Link this two subgroups

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OVERALL VIEW OF OSI MODEL

NETWORK

DATA LINK

PHYSICAL

TRANSPORT

SESSION

PRESENTATION

APPLICATION

SENDER RECEIVER

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Ethernet LANEthernet LAN WAN

NETWORK

DATA LINK

PHYSICAL

TRANSPORT

SESSION

PRESENTATION

APPLICATION

NETWORK

DATA LINK

PHYSICAL

TRANSPORT

SESSION

PRESENTATION

APPLICATION

NETWORK

DATA LINK

PHYSICAL

Router

NETWORK

DATA LINK

PHYSICAL

Router

SENDER RECEIVER

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NETWORK NETWORKNETWORK NETWORK

DATA LINK DATA LINKDATA LINK DATA LINK

PHYSICAL PHYSICALPHYSICAL PHYSICAL

TRANSPORT TRANSPORT

SESSION SESSION

PRESENTATION PRESENTATION

APPLICATION APPLICATION• File transfer, access,

and management• Mail services

• Directory services• Network virtual

terminal


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION


APPLICATION APPLICATION

- Translation- Encryption

- Compression


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



• Dialog control


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION




Router Router

1050 MB downloaded2GB data

2GB dataDownload starting from 1000MB

Synchronization

DATA

SENDER RECEIVER

......................100MB

200MB

300MB Check points

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TRANSPORT TRANSPORT

SESSION SESSION



Segmentation


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Connection control- Error control


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Logical addressing- Routing


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Physical addressing


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Error control- Flow control

- Access control


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Representation of bits- Data rate

- Physical topology- Transmission mode


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Syncronization of bits- Line Configuration


Router Router

DATA

SENDER RECEIVER

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Router Router




TRANSPORT TRANSPORT

SESSION SESSION



The physical layer remove its corresponding header.

DATADATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



The router removes the data link information and

sends it up to the network layer.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



The router uses the destination IP address to determine where to send the packet next.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



The router encapsulates the data with the proper data

link information for the WAN.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Physical layer transmit the data over the

network


Router Router

DATA

SENDER RECEIVER

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Router Router




TRANSPORT TRANSPORT

SESSION SESSION



In the same way data passes

through the 2nd router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



The physical layer remove its corresponding

header.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



Remove the data link header and tailer and converts frames back

into IP packets.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



Remove the IP header, converts the packets

back into segments and passes them back to

transport layer.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Reassemble


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION




Router Router

- Service-point addressingDATA

SENDER RECEIVER

A’s Chat window

B’s Chat window

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TRANSPORT TRANSPORT

SESSION SESSION



Uses the session information to determine

which communication stream this data belongs

to.


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- Decompression- Decryption - Translation


Router Router

DATA

SENDER RECEIVER

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TRANSPORT TRANSPORT

SESSION SESSION



- The application layer reads the original command that the

application layer on the sender sent.


Router Router

DATA

SENDER RECEIVER

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CONCLUSION

• The OSI model is more of a theoretical model. • The practical internet uses the TCP/IP model ..

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1. Computer Network – A system approch- Larry L Peterson & Bruce S. Davie

2. Computer Networks(4th edition)- Tannenbaum

3. Data Communications and Networking (4th edition)- Behrouz A. Forouzan

4. http://en.wikipedia.org/wiki/OSI_model5. http://www.roseindia.net/technology/networking/osi.shtml 6. http://www.webopedia.com/quick_ref/OSI_Layers.asp7. http://www.tech-faq.com/osi-model.html

http://en.wikipedia.org/wiki/OSI_model

http://www.roseindia.net/technology/networking/osi.shtml(accessed

http://www.webopedia.com/quick_ref/OSI_Layers.asp(accessed

http://www.webopedia.com/quick_ref/OSI_Layers.asp(accessed

http://www.tech-faq.com/osi-model.html

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THAN

K YO

U

OSI MODEL CONCEPT

Education

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