osi model description

1. PLACEMENT TRAINING
CUM
INTERNSHIP PROGRAM
By -:
Divanker Saxena
1900290310054
Secn A , ECE

2. INTRODUCTION
We were given just the brief introduction of every topic of the placement required
skills.
4 basic subject were taken up for :
DBMS
1 PROGRAMMING LANGUAGE ( Python )
DSA ( data structures and Algorithms )
QALR ( Qualitative Aptitude And Reasoning )

3. In presentation ,
one needs to select any technical subject from any branch of engineering ….
And present it .
So here ,
I would be disscusing a topic from DCN
(data communication networks) in this session .
It is a departmental elective for electronics and communication branch of engineering .

4. ISO/OSI MODEL
Known as OPEN SYSTEM NETWORKS Model
By International Standard Organization

5. DATA COMMUNICATION STANDARDS
• These are defined to ensure Orderly exchange of data and are of two types as
below -:
• CLOSED SYSTEMS
(confediancially Manufactured and controlled by one company only )
Eg : Apple Macintosh
• OPEN SYSTEMS
(company provides compatible software to everyone )
Eg: IBM Computers

6. OPEN SYSTEMS
• Layered network structure is used here
• They are of three types –
ISO/OSI ( 7 layered network )
TCP/IP ( 5/4 layered network )
CISCO ( 3 layered network )

7. ISO/OSI MODEL
Known as OPEN SYSTEM NETWORKS Model
By International Standard Organization

8. INTRODUCTION
• OSI Model is not a protocol
• It uses 7 layers
• 4 layers are used for Data communication and are linked directly
• Whereas other 3 layers i.e
Physical layer ; network Layer and data link layer does not communicate/linked
directly .

9. : 7 LAYERS OF OSI

10. N/W
source Destination
Peer to peer Data communication
Peer to peer Data communication
Peer to peer Data communication
Peer to peer Data communication
D
o
w
n
w
a
r
d
f
l
o
w
U
p
w
a
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f
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w
: Data flows in
downwards order at
SOURCE and upwards
order at DESTINATION

11. PHYSICAL LAYER :
• Lowest layer in OSI .
• Tx of unstructured bits by using Line Coding , Bit Rate & Bit Synchronization.
• Responsiblities :
1. Types of Tx :
1. baseband 2. Passband
1. Tx Modes :
1. Simplex 2. Duplex
1. Decides Types of Connection
2. Pin Assingments
3. Timings
4. Max & Min Voltages
5. Physical Electrical Mechanical
6. Data unit : unstructured Bits
7. Device :- HUB / Repeaters
8. HUB :
1. active(Repeaters) 2. Passive (connectors)

12. DATA LINK LAYER :
It is responsible for error free communication and node to node delivery
 It provides
1. Final framing
2. Synchhronization
3. Flow of data
4. Error detection& correction
5. Physical Adressing
 Functions
1. Line Control
2. Flow Control
3. Error Control
Data Unit : Frame

13. NETWORK LAYER
• Provides the details that enable data to be routed between devices
• Responsiblities :
1. IP Adressing of Source &Destination
2. Routiong
• Data Unit :- Packet
• Device :
1. Adaptable Router
2. Non - Adaptable Router

14. TRANSPORT LAYER
1. End to end integrity of Data
2. Responsiblities :
 Messsage routing
 Segmenting
 Error recovery
 Mutiplexing
 Highest layer of data communication
3. two types of services :
• Connection oriented
• Connection less
Provides data tracking & connection of low control .

15. SESSION LAYER
1) Responsiible for network avaiblity and job management
2) Second highest layer of Data Communication
3) Jobs file transfer, network log on & off, &user Authenticatiojn
4) Responsiblities :
Dail Log Control
Synchronizzation

16. PRESENTATION LAYER
1) Syntax conversion to present the Data
2) Third Highest layer of data communication
3) Format the data .
4) Key Responsiblities :
 Translation
 Encryption
 Compression

17. APPLICATION LAYER
1) Highest layer in OSI
2) 4th Highest layer of data communication
3) Access the network to OSI
4) Provides distributed information services and controls the activities
5) Two types of service elements :
 CASE (common Applicationn service elements )
 SASE ( Special Application service Elements )

18. : END OF
“ OSI MODEL ”