| OSI Model | ||||
|---|---|---|---|---|
| Data unit | Layer | Function | ||
| Host layers |
Data | 7. Application | Network process to application | |
| 6. Presentation | Data representation, encryption and decryption, convert machine dependent data to machine independent data | |||
| 5. Session | Interhost communication, managing sessions between applications | |||
| Segments | 4. Transport | Reliable delivery of packets between points on a network. | ||
| Media layers |
Packet/Datagram | 3. Network | Addressing, routing and (not necessarily reliable) delivery of datagrams between points on a network. | |
| Bit/Frame | 2. Data link | A reliable direct point-to-point data connection. | ||
| Bit | 1. Physical | A (not necessarily reliable) direct point-to-point data connection. | ||