Computer Networks - BSCS Notes

Computer Networks — Complete BSCS Notes

Analogue and Digital Transmission

Analogue Transmission: Continuous signal transmission.
Example: Radio waves.
Digital Transmission: Data sent in binary form (0 and 1).
Example: Computer communication.
Noise: Unwanted signal disturbance.
Media: Twisted pair, coaxial cable, fiber optics, wireless.

Encoding & Transmission Types

Encoding: Converting data into signal format.
Examples: NRZ, Manchester Encoding.
Asynchronous: Start and stop bits used.
Synchronous: Data transmitted in blocks with clock synchronization.

Protocol Design Issues

Definition: Rules for communication between devices.
Issues: Error control, flow control, sequencing, addressing.

Network Architectures

OSI Model: 7 layers
Physical
Data Link
Network
Transport
Session
Presentation
Application
TCP/IP: 4 layers
Network Access
Internet
Transport
Application

LAN & MAC Layer Protocols

Ethernet: Most common LAN technology.
Token Ring: Uses token passing.
MAC: Controls access to transmission medium.
Multiplexing: Multiple signals on one channel.

Switching, IP Networks & Routing

Switching: Circuit switching, packet switching.
Inter-networking: Connecting multiple networks.
Routing: Finding best path.
Bridging: Connects LAN segments.

Transport Layer

TCP: Reliable connection-oriented protocol.
UDP: Fast connectionless protocol.
Example: TCP for websites, UDP for video streaming.

Network Security Issues

Threats: Sniffing, spoofing, MITM attacks, DDoS.
Solutions: Firewall, VPN, encryption, IDS.

Programming Labs / Projects

Examples:
Socket programming
Client-server chat app
Protocol simulation
Routing algorithm implementation