OSI Model
Computers · OSI मॉडल
📋Quick Overview
The OSI (Open Systems Interconnection) Model is a 7-layer framework for understanding network communication. Developed by ISO in 1984. Each layer performs a specific function — from physical transmission (Layer 1) to application services (Layer 7). The TCP/IP model is a simpler 4-layer practical model used on the internet.
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7 OSI Layers (bottom to top): Physical, Data Link, Network, Transport, Session, Presentation, Application
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TCP/IP has 4 layers: Network Access, Internet, Transport, Application
📖OSI Model
| Layer | Name | Function | Protocol |
|---|---|---|---|
| 7 | Application | User interface, email, browsing | HTTP, FTP, SMTP, DNS |
| 6 | Presentation | Encryption, compression, format | SSL/TLS, JPEG, ASCII |
| 5 | Session | Manages sessions/connections | NetBIOS, RPC |
| 4 | Transport | End-to-end delivery, error control | TCP, UDP |
| 3 | Network | Routing, IP addressing | IP, ICMP, ARP |
| 2 | Data Link | MAC addressing, framing | Ethernet, Wi-Fi, PPP |
| 1 | Physical | Bit transmission, cables | Cables, Hubs, Fiber optic |
📝Key Points
- •7: HTTP, FTP, SMTP, DNS
- •6: SSL/TLS, JPEG, ASCII
- •5: NetBIOS, RPC
- •4: TCP, UDP
- •3: IP, ICMP, ARP
- •2: Ethernet, Wi-Fi, PPP