1. Service Primitives
Six service primitives that provide a simple connection-oriented service
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2. A simple client-server interaction using acknowledged datagrams.
Service Primitives
A simple client-server interaction using acknowledged datagrams.
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3. OSI Model
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4. 2-1 LAYERED TASKS A network model is a layered architecture
Task broken into subtasks
Implemented separately in layers in stack
Functions need in both systems
Peer layers communicate
Protocol:
A set of rules that governs data communication
It represents an agreement between the communicating
devices
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5. Layered Architecture A layered model
Each layer performs a subset of the required communication functions
Each layer relies on the next lower layer to perform more primitive functions
Each layer provides services to the next higher layer.
Each layer provides services to the next higher layer
Changes in one layer should not require changes in other layers
The processes on each machine at a given layer are
called peer-to-peer process
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6. Tasks involved in sending a letter
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7. 2-2 THE OSI MODEL
Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards.
An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.
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8. ISO is the organization. OSI is the model.
Note
ISO is the organization. OSI is the model.
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9. Seven layers of the OSI model
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10. The interaction between layers in the OSI model
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11. An exchange using the OSI model
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12. Note The physical layer is responsible for movements of
individual bits from one hop (node) to the next.
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13. Function of Physical layer
Physical characteristics of interfaces and media
Representation of bits
Data rate
Synchronization of bits
Line configuration (point-to-point or multipoint)
Physical topology (mesh, star, ring or bus)
Transmission mode ( simplex, half-duplex or duplex
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14. Physical layer
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15. Note
The data link layer is responsible for moving frames from one hop (node) to the next.
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16. Data link layer
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17. Hop-to-hop delivery
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18. Function of data link layer
Framing
Physical addressing
Flow control
Error control
Access control
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19. the source host to the destination host.
Note
The network layer is responsible for the delivery of individual packets from
the source host to the destination host.
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20. Network layer
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21. Source-to-destination delivery
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22. Function of network layer
Source-to-destination delivery
Responsible from the delivery of packets from the original
source to the final destination
Functions
Logical addressing
routing
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23. Transport layer
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24. Note
The transport layer is responsible for the delivery of a message from one process to another.
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25. Function of transport layer
Port addressing
Segmentation and reassembly
Connection control ( Connection-oriented or connection-less)
Flow control
Error control
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26. Reliable process-to-process delivery of a message
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27. Session layer
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28. Note
The session layer is responsible for dialog control and synchronization.
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29. Function of session layer
It establishes, maintains and synchronize the interaction between communicating system
Dialog control
Synchronization (checkpoints)
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30. Presentation layer
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31. Note
The presentation layer is responsible for translation, compression, and encryption.
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32. Function of presentation layer
Concerned with the syntax and semantics of the information exchanged between two system
Translation ( EBCDIC-coded text file ASCII-coded file)
Encryption and Decryption
Compression
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33. Application layer
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34. Note
The application layer is responsible for providing services to the user.
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35. Function of application layer
Network virtual terminal (Remote log-in)
File transfer and access
Mail services
Directory services (Distributed Database)
Accessing the World Wide Web
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36. Summary of layers
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37. OSI layer-Summary
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