OSI Model-Network (updated version) .pdf

OSI Model

1. Networking Fundamentals
«Open system interaction model»
❑The OSI model is ageneral framework that define how we connect our
devices and enables network protocols, software, and systems to be
designed around a general set of guidelines.
❑Common guidelines allow higher probability of system compatibility and
logical traffic flow. In other words, if we all play by the same rules, everyone
will get alongwith as few errors as possible.
❑OSI Model

2. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer

3. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Data wanted to be sent in the
network(https header , files...)
•Lunshed by an applications
like(browsers , games..)

4. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Data compression/
decompression
•Data encryption/decryption
•Defining data format
(JPG,HTML,TXT...)

5. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Creating , terminating
logical sessions .
•Defining communication
modes(single, half-duplex,
full-duplex)

6. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•How to Transport the data?
•Reliably
•Fast & unreliably
•L4 header

7. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Routing protocols
•choosing the best path
for routing depending
in used protocol

8. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Data Encoding from
Ascii to binary ,
Decoding binary to Ascii

9. OSI LAYERS
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer
•Physical connection
(Ethernet connections
802.3, wireless
connections 802.11)

10. OSI & TCP/IP Models

11. OSI & TCP/IP Models
•The TCP/IP model, which is more pragmatic and widely used in current
networks, particularly the Internet, consists of four layers: Network
Access, Internet, Transport, and Application.
Key differences between OSI model and TCP/IP model :
•Although both models aim to facilitate network communication, the
TCP/IP model is based on practical and implemented protocols, such as
TCP and IP, whereas the OSI model remains a theoretical reference
framework.
•The main difference lies in their application: the OSI model is primarily
used for understanding and standardizing network communication
processes, while the TCP/IP model is used for the actual implementation
of networks, especially in practical contexts like the Internet.

12. OSI VS TCP/IP
TCP/IP
Application
Layer
Host-To-Host
Transport
Internet Layer
Network
interface Layer
OSI
Application
Layer
Presentation
Layer
Session Layer
Transport
Layer
Network Layer
Data Link Layer
Physical Layer

13. Encapsulation & Decapsulation

14. Encapsulation & Decapsulation
•Encapsulation: is the process of adding additional information when data
is traveling in an OSI or TCP/IP model
•Decapsulation:reverses the process by removing the info one by one, so a
destination device can read the original data.

15. Encapsulation
https://www.youtube.com
DATA (https header)
DATA (https header)L4 header
L3 header DATA (https header)L4 header
DATA (https header)L4 headerL3 headerL2 header L2 trailer
HASH PAYLOAD

16. Encapsulation
https://www.youtube.com
DATA (https
header)
DATA (https
header)
L4 header
L3 header
DATA (https
header)
L4
header
DATA (https
header)
L4
header
L3
header
L2
header
L2 trailer
HASH
PAYLOAD
SEQUENCE
PACKET
FRAME

17. Decapsulation
https://www.youtube.com
DATA (https header)
DATA (httpsheader)L4 header
L3 header DATA (https header)L4 header
DATA (https header)L4 headerL3 headerL2 header L2 trailer
HASH PAYLOAD

18. COMMON ATTACKS IN THE OSI MODEL

19. COMMON ATTACKS IN THE OSI MODEL