The Seven Layers of the OSI Model
| 7 |
Application
Network Process to Application |
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- Provides network services processes to application processes (such as electronic mail, file transfer,…)
- Provides user authentication
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| 6 |
Presentation
Data Representation |
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- Ensures that data is readable by receiving system
- Formats data
- Structures data
- Negotiates data transfer syntax for application layer
- Provides encryption
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| 5 |
Session
Interhost Communication |
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- Establishes, manages, and terminates sessions between applications
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| 4 |
Transport
End-to-end Connections |
Segment |
- Handless transportation issues between hosts
- Ensures data transport reliability
- Establishes, maintains, and terminates virtual circuits
- Provides reliability trough fault detection and recovery flow control
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| 3 |
Network
Data Delivery |
Packet |
- Routes data packets
- Selects best path to deliver data
- Provides logical addressing and path selection
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| 2 |
Data Link
Access to Media |
Frame |
- Defines how data is formatted for transmission and how access to the network is controlled
- Provides error detection
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| 1 |
Physical
Binary Transmission |
Bit |
- Defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating physical link
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Encapsulation 7 -> 1
De-Encapsulation 1 -> 7
