Network Topologies and Devices
Computers in a network are connected in different layouts. We study star, bus and ring topologies and devices such as the modem, router and switch.
All topics (3 of 11)
Chapter 1. Computer networks
Chapter 2. Information security
Chapter 3. Creating web pages
A network topology is the layout of computers and communication links. In a bus topology all computers are connected to one shared cable: it is cheap, but if the cable is damaged the whole network stops. In a ring topology the computers are linked in a circle one after another and data travels in one direction.
The star topology is the most common today. Each computer is connected by its own cable to a central device (a switch or a router). If one computer fails the others keep working; the drawback is that if the central device breaks, the network stops. A school computer lab is usually built in exactly this way.
Network devices do different jobs. A network card connects a computer to the network. A switch links devices inside one network and sends data only to the computer that needs it. A router connects different networks, for instance a home network and the internet, and chooses the path for data.
A modem converts a digital signal into a signal that travels over a telephone or optical line, and back again. A home Wi-Fi device often combines the functions of a modem, a router and a wireless access point. Data speed is measured in bits per second: at 100 Mbit/s about 12.5 megabytes are transferred every second.
Key takeaways
- Topology is the layout of network elements: bus, ring or star.
- The star topology is the most reliable and widespread.
- A switch works inside one network, a router works between different networks.
- Speed is measured in bit/s; 8 bits = 1 byte.
Practice tasks
- Draw diagrams of the bus, ring and star topologies in your notebook and write one advantage and one disadvantage of each.
- Find out which topology your school computer lab uses and list the devices that are used.
- Calculate roughly how many seconds a 600 MB file takes to download at 80 Mbit/s (1 byte = 8 bits).
Review questions
Test yourself: think first, then reveal the answer.
1Why is the star topology more reliable than the bus?Show answerHide answer
Each computer has its own cable, so if one cable or computer fails the others keep working.2What is the main difference between a switch and a router?Show answerHide answer
A switch connects devices within one network, while a router connects different networks (for example a home network and the internet).
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