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Network
OSI Model
The OSI (Open System Interconnect) Model was developed in 1984 as an open standard to promote network interconnection and interoperability.
| Layer | Function | Examples |
|---|---|---|
| 7. Application | End User : Support for applications | HTTP, FTP, SMTP (email) |
| 6. Presentation | Syntax : Protocol conversion, structures data for the application | ASCII, JPEG, etc. |
| 5. Session | Sync & Ports : Establishes, manages and terminates sessions & connections | NFS, SQL |
| 4. Transport | End to End Connection : Is concerned with message integrity between source and destination | TCP, UDP |
| 3. Network | Packets : Combines messages into packets, adding routing information | IP, IPX |
| 2. Data Link | Frames : Handles flow control, sequencing, errors | MAC |
| 1. Physical | Cables : Provides electrical and mechanical connections to the network | cables and NIC |