The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers.

2. Protocol is the law in networking world
Network devices
oNIC(network interface card)
oRouter
oSwitch
oBridge
o ...........etc
Network companies (microsoft_ junipr _redhat _cisco)

3. Network Devices
Hub
NIC
Switch
Router
Bridge

4. Networking Companies

6. (OSI)MODEL
Open Systems Interconnect

7. • A Model of How Protocols and Networking
components could be made.
• “Open” means ;can be used by anyone.
• (OSI) Model is 7 layers.
• OSI layers is logic.

8. Breaks down the complex.
Study complex system.
Developing system.
Helps in troubleshooting.
Each layer has aspecific funcition

9. • Application .All
• Presention .People
• Session .Seem
• Transport .To
• Network .Need
• Data link .Data
• Physical .Processing

12. Microsoft & Redhat
Cisco & Juniper

14. • Interface Application
• Examples
o HTTP: browsing protocol.
o FTP: file transfer protocol.
o SMTP: simple mail transfer protocol.

15. • Format of data .
• Compression and Decompression of data .
• Encryption and Decryption of data.

16. • Set sessions between applications .
example : msn messenger
• Specifies communication mode .
(simplex – half duplex – full duplex)
• Data stream :010010101010101010101010011110001010100

18. • Tasks :
- Flow control
- Error recovery
• Protocols :
-TCP
-UDP
• Segments segment1 TCP segment2 TCP

19. • Tasks :
-Best way to move data
- Routing
- IP addressing
• Packets
segment1 TCPIP

20. Data Link
Logical Link
Control
Media Access
Control
oLLC: Frame network layer.
oLLC: Network layer protocol.
oMAC: Address the frame.
oMac: Make H & T .
oSwitch.
oFrames segment1 TCPIPHeader Tailer
Addresses Error
Detection

21. Mac Address

22. • Send & Receive Bits
• Hub
segment1 TCPIPHeader Tailer
001010101010101010101010101010101010101010101010101000