- Published on
OSI model
The OSI Model (Open Systems Interconnection Model) is a conceptual framework that standardizes how different computer systems communicate over a network. It divides the communication process into 7 layers, each responsible for specific network functions.
Here’s a quick overview:
| Layer | Name | Primary Function | Example Protocols / Technologies |
|---|---|---|---|
| 7 | Application | Interface for end-user applications to access network services | HTTP, HTTPS, FTP, SMTP, DNS |
| 6 | Presentation | Data translation, encryption, compression | SSL/TLS, JPEG, ASCII, MPEG |
| 5 | Session | Establishes, manages, and terminates sessions | NetBIOS, RPC, PPTP |
| 4 | Transport | Reliable or unreliable delivery, flow control | TCP, UDP |
| 3 | Network | Logical addressing and routing | IP, ICMP, OSPF, BGP |
| 2 | Data Link | Physical addressing, error detection | Ethernet, MAC, PPP, ARP |
| 1 | Physical | Transmission of raw bits over a physical medium | Cables, Hubs, NICs, Wi-Fi (PHY) |
🔄 Simplified Flow
- Sender: Application → Presentation → Session → Transport → Network → Data Link → Physical
- Receiver: Physical → Data Link → Network → Transport → Session → Presentation → Application
🧠 Mnemonic to Remember
All People Seem To Need Data Processing (Application → Presentation → Session → Transport → Network → Data Link → Physical)