Computer Networks
CN Part-1
- What is a Computer Network?
- Goals and Applications of Computer Networking
- Computer Network Components
- Types of Computer Networks
- Network Topology
- Difference between Client Server and Peer to Peer Network
- Layered Architecture in Computer Networks
- Protocol Hierarchy in Computer Networks
- Interfaces and Services in Computer Networks
- Connection Oriented and Connectionless Services
- Service Primitives
- OSI Model
- TCP/IP Model
- Difference between OSI Model and TCP/IP Model
- Encapsulation and Decapsulation in Computer Networks
- Queueing Models in Computer Network
CN Part-2
Difference Between OSI Model & TCP/IP Model
Pehle Basic Samjho:
Dono models ka kaam same hai — data ko ek device se doosre device tak pahuchana — lekin kaise karte hain usmein difference hota hai.
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OSI Model ek theoretical model hai — mainly samjhane aur design ke liye banaya gaya.
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TCP/IP Model ek practical model hai — jo aaj ke internet mein real mein use hota hai.
OSI Model Kya Hai?
OSI (Open Systems Interconnection) Model ek 7-layer ka model hai jise ISO ne banaya tha. Yeh sirf ek standard model hai, real networks mein directly use nahi hota.
OSI ki 7 Layers:
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Physical – bits bhejne ka kaam (0 aur 1)
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Data Link – MAC address, frames
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Network – IP address, routing
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Transport – TCP/UDP, ports, segmentation
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Session – sessions establish/close
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Presentation – data ko encrypt/format karna
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Application – apps jaise browser, email client
TCP/IP Model Kya Hai?
TCP/IP (Transmission Control Protocol / Internet Protocol) Model ek 4-layer model hai jo actual Internet aur real networks mein use hota hai.
TCP/IP ki 4 Layers:
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Network Access Layer – bits + MAC address + frame
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Internet Layer – IP address aur routing
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Transport Layer – TCP/UDP, port number, reliability
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Application Layer – browser, Gmail, YouTube, etc.
OSI vs TCP/IP Diagram
OSI vs TCP/IP – Detailed Comparison
| Feature | OSI Model | TCP/IP Model |
|---|---|---|
| Full Form | Open Systems Interconnection | Transmission Control Protocol / Internet Protocol |
| Layers | 7 Layers | 4 Layers |
| Created By | ISO (International Organization) | DARPA (U.S. Dept. of Defense) |
| Use | Theoretical Model (samjhane ke liye) | Practical Model (real mein use hota hai) |
| Application Layer | 3 Layers mein divided (App, Pres, Sess) | 1 hi Application Layer hai |
| Transport Protocols | TCP/UDP dono support karta hai | TCP/UDP dono use karta hai |
| Network Interface | Data Link + Physical alag hote hain | Dono ko combine karke Network Access |
| Protocol Dependency | Protocol independent | Protocol specific (IP, TCP, UDP) |
| Use Today | Sirf teaching aur theory ke liye | Internet aur duniya ke networks mein use |
| Design Flexibility | Zyada flexible hai | Thoda fixed structure hai |
Ek Simple Real-Life Analogy
OSI Model: Jaise ek manual guide hai jo batata hai ki parcel kaise bhejna hai, har step detail mein likha hota hai.
TCP/IP Model: Jaise Amazon ka actual delivery process — yeh guide ko use karke real mein parcel bhej deta hai.
Real Example – Website Access Karna (Google.com)
| Step | OSI Model Layers | TCP/IP Layers | Kaam Kya Hota Hai |
|---|---|---|---|
| 1 | Application, Presentation, Session | Application Layer | Browser request bhejta hai |
| 2 | Transport | Transport Layer | TCP port 443 use hota hai (HTTPS) |
| 3 | Network | Internet Layer | IP address add hota hai |
| 4 | Data Link + Physical | Network Access Layer | Data Wi-Fi ya cable se bheja jaata hai |
Summary
| Feature | OSI Model | TCP/IP Model |
|---|---|---|
| Layers | 7 | 4 |
| Design Purpose | Educational & Conceptual | Practical & Implemented |
| Internet Usage | Nahi hota | Internet isi pe chalta hai |
| Flexibility | Zyada flexible | Protocol-defined |
| Use in College | Concept samjhane ke liye | Real implementation samjhne ke liye |
Conclusion
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OSI Model achha hai concepts samajhne ke liye.
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TCP/IP Model actual world mein use hota hai — internet, websites, email, YouTube sab isi pe kaam karte hain.
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Dono models help karte hain students ko networking clearly samajhne mein.