A Brief Overview of Computer Networks
A computer network is a collection of interconnected devices (computers, servers, routers), that communicate to exchange data, services and resources across the globe.
A Brief History
- 1969 - ARPANET Launches
- 1974 - TCP Protocol Proposed Cerf & Kahn introduce TCP, enabling reliable communication across diverse networks.
- 1983 - ARPANET adopts TCP/IP; DNS system introduced to map domain names to IPs.
- 1989 - World Wide Web Invented Tim Berners-Lee creates HTTP and HTML, revolutionizing how we access and share information.
- 1993 - Mosaic Browser Released First graphical web browser makes the Internet user-friendly and widely accessible.
Data Communication
Data communication is the exchange of data between devices over a transmission medium. It relies on:
- Sender, Receiver, and Medium: These entities define the communication setup
- Protocols: Rules that ensure data integrity and order
- Bandwidth & Latency: Affect the speed and efficiency of transmission
Transmission Modes
Data can flow between devices in several ways:
- Simplex: One-way only (e.g., keyboard to CPU)
- Half-Duplex: Two-way, but only one direction at a time (e.g., walkie-talkies)
- Full-Duplex: Two-way simultaneous (e.g., Zoom calls)
Connection Types
Networks can be built with different connection structures:
- Point-to-Point: Direct link between two nodes. It is fast and simple
- Multipoint: Multiple nodes share a link. It is efficient but complex
Types of Networks
- LAN (Local Area Network): Small-scale, such as office or home networks. Example - A JioFiber router in your home
- MAN (Metropolitan Area Network): Covers a city or campus. Example - Fiber infrastructure across Bengaluru city managed by local ISPs or government
- WAN (Wide Area Network): Large-scale, spans countries or continents (like the Internet).
- PAN (Personal Area Network): Close-range, like Bluetooth-based systems
Network Models
| OSI Model (7 Layers) | TCP/IP Model (4 Layers) | Function of the Layer |
|---|---|---|
| 7. Application | Application | Interface for end-user software (e.g. HTTP, FTP, SMTP, DNS); handles network services |
| 6. Presentation | Application | Translates data format (e.g. encryption, compression, encoding) |
| 5. Session | Application | Manages sessions, connections, and dialogs between applications |
| 4. Transport | Transport | Provides reliable data transfer with error handling and flow control (e.g. TCP, UDP) |
| 3. Network | Internet | Handles routing, IP addressing, and packet forwarding across networks |
| 2. Data Link | Network Access | Manages physical addressing (MAC), framing, and error detection at node-to-node level |
| 1. Physical | Network Access | Handles transmission of raw bits over a physical medium (cables, signals, etc.) |
Conclusion
Understanding the basics of computer networking empowers software engineers to build more robust, scalable, and efficient applications.