Learning Objectives
- Explain why communication and networking matter to business.
- Define data communication and its five components.
- State the characteristics of effective data communication.
- List the advantages and disadvantages of computer networks.
- Preview media, types, topologies, hardware, and wireless.
Next: media and transmission, types and topologies, protocols and hardware, wireless.
Why networking matters
Without networks, every computer is an island. Organizations network to share resources (printers, files, internet links), communicate (email, chat), coordinate (ERP, POS), and reach customers. Cost per user falls when many devices share one connection and one server.
Data communication
Data communication is the exchange of data between two devices through a transmission medium, following agreed rules.
Five components
- Message — the data being sent (text, numbers, images, audio, video).
- Sender — the device that sends the message (computer, phone, camera).
- Receiver — the device that receives it.
- Transmission medium — the physical path: copper cable, fiber optic, or radio waves.
- Protocol — the agreed rules for communication (format, timing, error checking). Without a common protocol, two connected devices cannot understand each other, just as two people speaking different languages cannot.
flowchart LR
S[Sender] -->|Message encoded as signals| M[Transmission medium]
M --> R[Receiver]
P[Protocol: shared rules] -.-> S
P -.-> R
Bandwidth is how much data the path can carry per second; latency is delay.
Characteristics of effective data communication
- Delivery — data must reach the correct receiver.
- Accuracy — data must arrive without errors.
- Timeliness — data must arrive in time to be useful (late video or voice is useless).
- Jitter — the variation in arrival time of packets should be small, especially for calls and video.
Direction of data flow
- Simplex — one direction only (keyboard to computer, TV broadcast).
- Half-duplex — both directions, but one at a time (walkie-talkie).
- Full-duplex — both directions at the same time (phone call, video meeting).
From communication to a computer network
A computer network is a set of devices plus the media and protocols that let them exchange data. Later chapters classify LAN/WAN, star/bus/ring, TCP/IP, switches and routers, and Wi-Fi.
Advantages and disadvantages of networks
| Advantages | Disadvantages |
|---|---|
| Resource sharing — one printer or internet line for all | Security risk — malware and intruders spread faster |
| Data sharing — everyone works from the same files | Setup and maintenance cost — cabling, devices, staff |
| Communication — email, chat, video meetings | Dependence — a failed server or switch stops work |
| Centralized backup and security management | Privacy concerns — activity can be monitored |
| Lower cost per user and easier software licensing | Need for skilled administration |
| Remote work and multi-branch operation |
Business applications
- Banking: branches, ATMs, and mobile apps connect to one core banking system.
- Retail: POS terminals send each sale to head office for stock and sales reporting.
- Education: campus networks deliver learning portals, online exams, and library access.
- Government: offices share citizen records for online services.
Nepal / business example
A supermarket in Pokhara with isolated tills cannot update stock in real time. A LAN plus a link to a head-office WAN turns those tills into one information system.
Scenario: a cooperative with five branches keeps member savings in separate desktop programs. A member who deposits in one branch cannot withdraw in another, and head office learns totals only at month-end. After networking the branches to one central server, any branch can serve any member, balances are always current, and the manager sees daily totals.
Key Takeaways
- Networks share resources and enable information systems that span locations.
- Data communication has five components: message, sender, receiver, medium, and protocol.
- Effective communication requires delivery, accuracy, timeliness, and low jitter.
- Networking brings sharing and lower cost, but also security, cost, and dependence risks.
- Unit 6 is the technical base for the internet (Unit 7).
Discussion Questions
- What resource does a small office share first: printer, files, or internet?
- Why do protocols matter if the cable is perfect?
- Is a mobile hotspot a LAN, a WAN, or both in practice?
Exam-Style Questions
Short answer
- Define data communication. List its five components.
- Differentiate between simplex, half-duplex, and full-duplex with examples.
- Why is a protocol necessary in data communication?
Long answer
- Explain the importance of computer networks for a business organization, with advantages and disadvantages.
- Describe the components and characteristics of an effective data communication system.
