OSI Model
- Feb 26
- 1 min read
✍️ OSI Model — Layers Explanation
✅ OSI Model क्या है
OSI (Open Systems Interconnection) model networking communication को 7 layers में divide करता है ताकि data transmission व्यवस्थित तरीके से हो सके।
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🔵 1️⃣ Physical Layer (Layer 1)
✔ Function
Data को bits (0,1) में transmit करना
Electrical signals / cables / hardware
✔ Examples
Cable, Hub, Repeater
👉 यह hardware layer है।
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🔵 2️⃣ Data Link Layer (Layer 2)
✔ Function
Error detection
Framing
MAC addressing
✔ Examples
Switch, Ethernet
👉 Reliable node-to-node communication।
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🔵 3️⃣ Network Layer (Layer 3)
✔ Function
Routing
Logical addressing (IP address)
Path selection
✔ Examples
Router, IP protocol
👉 Best path decide करता है।
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🔵 4️⃣ Transport Layer (Layer 4)
✔ Function
End-to-end delivery
Error control
Flow control
Segmentation
✔ Examples
TCP, UDP
👉 Reliable communication सुनिश्चित करता है।
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🔵 5️⃣ Session Layer (Layer 5)
✔ Function
Session establish, maintain, terminate
Synchronization
👉 Devices के बीच connection manage करता है।
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🔵 6️⃣ Presentation Layer (Layer 6)
✔ Function
Data format conversion
Encryption / Decryption
Compression
👉 Data को readable format में बदलता है।
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🔵 7️⃣ Application Layer (Layer 7)
✔ Function
User services
Network applications
✔ Examples
HTTP, FTP, SMTP, Email, Browser
👉 User interaction layer।
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✅ Data Flow (Exam Concept)
Application → Presentation → Session → Transport → Network → Data Link → Physical
(Receiving side पर reverse)
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✅ Mnemonic (Exam Trick)
⭐ Please Do Not Throw Sausage Pizza Away
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✅ Conclusion
OSI model communication को modular बनाता है, troubleshooting आसान करता है और networking standards define करता है।
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