Computer Networks Notes
Subject Overview
Computer Networks covers data communication concepts and network topologies, wireless transmission and switching techniques with OSI/
Subject at a glance
4
Units
29
Topics
5
Credits
4
Infographics
Unit-wise Syllabus
4 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Digital and analog transmission
- parallel/serial and synchronous/asynchronous modes
- simplex/half-duplex/full-duplex communication
- multiplexing
- LAN/MAN/WAN types
- network topologies (bus, star, ring, mesh, tree, hybrid)
- wired communication channels
Simplex
One way only
Keyboard to computer, TV broadcast
Half-duplex
Both ways, one at a time
Walkie-talkie
Full-duplex
Both ways at once
Telephone call
Study guide
This unit covers data communication: digital and analog transmission, parallel and serial and synchronous and asynchronous modes, simplex, half- and full-duplex communication, multiplexing, LAN, MAN and WAN and the network topologies, along with wired channels. Compare the topologies by cost, reliability and ease of installation.
- Microwave/infrared/laser/radio/satellite transmission
- Bluetooth
- frequency spectrum
- circuit/message/packet switching
- OSI reference model
- TCP/IP reference model
- comparison of OSI and TCP/IP
Top
Application, presentation, session
Application
Middle
Transport
Transport (TCP, UDP)
Routing
Network
Internet (IP)
Bottom
Data link, physical
Network access
Study guide
You study wireless transmission (microwave, infrared, laser, radio, satellite, Bluetooth), the frequency spectrum, circuit, message and packet switching and the OSI and TCP/IP reference models with a comparison. Learn the layers of both models with the function of each.
- Services to the network layer
- framing
- error control (detection and correction codes)
- flow control
- SLIP and PPP
- FDM/TDM/CDMA multiplexing
FDM
Different frequency bands
Radio, cable TV
TDM
Different time slots
Digital telephony
CDMA
Different codes on the same band
Mobile networks
Study guide
You study the data link layer: services, framing, error detection and correction codes, flow control, SLIP and PPP and FDM, TDM and CDMA multiplexing. Practise parity and CRC examples.
- CSMA/CD/CA
- IEEE 802.3 Ethernet
- Gigabit Ethernet
- IEEE 802.4 Token Bus
- IEEE 802.5 Token Ring
- network layer design issues
- routing algorithms (optimality principle, shortest path)
- congestion control policies
- internetworking concept
Full form
Collision detection
Collision avoidance
Used in
Wired Ethernet (IEEE 802.3)
Wi-Fi (IEEE 802.11)
Approach
Detect collision, stop, retry
Wait and signal to avoid collisions
Study guide
You study the MAC sublayer (CSMA/CD and CSMA/CA, IEEE 802.3, Gigabit Ethernet, Token Bus and Token Ring) and the network layer: design issues, routing algorithms, congestion control and internetworking. Practise a shortest-path routing example.
Why Computer Networks Matters
Networking is the backbone of the internet and cloud, and the OSI and TCP/IP models are asked in nearly every IT interview and are the base for certifications such as CCNA.
How to Prepare for Computer Networks
- Learn the OSI layers with protocols and devices in one table.
- Practise error detection and routing problems.
- Use a network simulator to try configurations.
Computer Networks: Frequently Asked Questions
What is CSMA/CD?
Carrier Sense Multiple Access with Collision Detection is the Ethernet method in which a device listens before transmitting and stops if it detects a collision.
What is the difference between circuit switching and packet switching?
Circuit switching sets up a dedicated path for the whole communication, while packet switching breaks data into packets that travel independently.