In a star topology, every device connects directly to a central switch or hub. All data passes through the central point. Most common topology in modern LANs.
Advantages: reliable — if one device fails, others unaffected; easy to add/remove devices; fast (dedicated connections); easy to troubleshoot
Disadvantages: if the central switch fails, the whole network fails; more cabling needed than bus; switch is expensive
Mesh Topology
Every Device Connected to Every Other
In a full mesh, every device connects to every other. In a partial mesh, only some devices have multiple connections. Very robust — data can reroute around failures.
Advantages: very reliable; no single point of failure; high fault tolerance; data takes shortest route
Disadvantages: very expensive — large amount of cabling; complex to set up and maintain
Used in: WANs, internet backbone, military networks, critical infrastructure
Bus & Ring Topologies
Older and Less Common Layouts
Bus: all devices connect to a single cable (backbone). Data travels in both directions; collisions possible. Simple and cheap but slow; if backbone breaks, whole network fails.
Ring: devices connected in a closed loop. Data travels one direction around the ring. Orderly — token passing controls access. If one device fails, the ring breaks (unless dual-ring).
Exam Practice
Have a go at this question
Edexcel-style question
A school is designing a new network. Explain why a star topology may be more suitable than a bus topology.
3 marks
In a star topology, if one device fails it does not affect others [1], whereas in a bus topology a break in the cable brings down the whole network [1]. Star is also faster since devices have dedicated connections to the switch [1].
Key Takeaways
What to Remember
Star: central switch; one failure doesn't affect others; switch failure = full outage
Mesh: very reliable; no single point of failure; expensive/complex
Bus: cheap but backbone failure = network failure; collisions slow it down
Star is the standard for modern LANs; mesh for WANs and critical systems