This topic introduces students to the basic concepts of computer networks, including different types of networks, network components, and the importance of networking in modern computing.
Introduction to Networks – Study Notes
1. What Is a Network?
| Term |
Definition |
| Network |
A collection of interconnected devices (nodes) that can share data, resources, and services. |
| Node |
Any device that can send, receive, or forward information (e.g., computer, printer, router, smartphone). |
| Link |
The physical or logical connection between nodes (cable, fiber, wireless signal, etc.). |
| Topology |
The arrangement of nodes and links in a network (e.g., star, mesh, bus). |
2. Core Network Concepts
| Concept |
Description |
Example |
| Bandwidth |
Maximum data rate a link can carry, measured in bits per second (bps). |
100 Mbps Ethernet |
| Latency |
Time for a data packet to travel from source to destination, measured in milliseconds (ms). |
20 ms round‑trip time for a LAN |
| Throughput |
Actual amount of data successfully transferred per unit time. |
80 Mbps observed on a 100 Mbps link |
| Protocol |
A set of rules governing communication. |
TCP, IP, HTTP |
| Addressing |
Identifiers that allow devices to locate each other. |
IPv4 address 192.168.1.10, MAC address 00:1A:2B:3C:4D:5E |
3. Network Types by Scope
| Scope |
Typical Size |
Common Uses |
| Personal Area Network (PAN) |
A few meters |
Bluetooth headphones, smartwatches |
| Local Area Network (LAN) |
Up to a building or campus |
Office computers, printers |
| Metropolitan Area Network (MAN) |
City‑wide |
Municipal Wi‑Fi, university campuses |
| Wide Area Network (WAN) |
Regional to global |
The Internet, corporate branch connections |
| Storage Area Network (SAN) |
Data‑center focused |
High‑speed storage access |
4. Network Topologies
| Topology |
Structure |
Advantages |
Disadvantages |
| Star |
All nodes connect to a central hub/switch |
Easy to add/remove nodes; failure isolated to a single link |
Central device is a single point of failure |
| Bus |
Nodes share a single backbone cable |
Simple, inexpensive |
Collisions; limited scalability |
| Ring |
Nodes form a closed loop; data travels in one direction (or both) |
Predictable performance |
Failure of one link breaks the ring (unless using a dual‑ring) |
| Mesh |
Each node can connect to multiple others |
High redundancy, fault tolerance |
Complex, costly |
| Tree (Hierarchical) |
Combination of star and bus; layers of switches |
Scalable, organized |
Requires careful planning; root failure impacts sub‑trees |
5. The OSI Model – 7 Layers
| Layer |
Primary Function |
Typical Protocols / Devices |
| 7 – Application |
End‑user services (email, web) |
HTTP, SMTP, FTP |
| 6 – Presentation |
Data formatting, encryption, compression |
TLS/SSL, JPEG, ASCII |
| 5 – Session |
Managing dialogs, synchronization |
NetBIOS, RPC |
| 4 – Transport |
End‑to‑end reliability, flow control |
TCP, UDP |
| 3 – Network |
Routing, logical addressing |
IP, ICMP |
| 2 – Data Link |
Frame handling, MAC addressing, error |
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