For systems interconnections in a network, and has 7 layers (from top to bottom):
- Application: Closest to user, e.g. HTTP, FTP...
- Presentation: Encryption/Decryption, Compression/decompression, e.g. jpeg, mpeg...
- Session: e.g. sync file transfers with checkpoints (to avoid restarting from beginning on failure).
- Transport: Flow and error control, e.g. TCP, UDP
- Network: breaks/assembleds data into packets, routing, e.g. IP
- Data link: connects devices that are physically in the same network, e.g. Ethernet, MAC
- Pyhsical: bit (raw data), e.g. cables
Organizes communication between devices over the internet, and has 4 layers (top to bottom):
- Application: HTTP, FTP. For process to process (by ports) communication.
- Transport: TCP, UDP. For host to host communication.
- Internet: IP addressig, routing. For communication between independent networks.
- Link: MAC address. For communication within the same network.