Network Topologies

Computer ScienceOCRGCSEUnit: 3.5 Fundamentals of Computer Networks
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The basics

The Network Layout Story

The Network Layout Story

Imagine you're designing a network for your school. How should you connect all the computers? Network topology is the arrangement of devices in a network - the "shape" of how everything connects. Think of it like planning the roads in a town! You could have all roads meeting at one central roundabout (Star topology), a single main road with houses along it (Bus topology), roads forming a circle (Ring topology), or a complex road network where everywhere connects to everywhere (Mesh topology). Each design has trade-offs between cost, reliability, and performance!
Spotlight
Deep Dive: Why Topology Matters

Network topology determines how data flows, what happens when failures occur, and how much the network costs:

Exam tip

Earn the mark scheme marks

Exam Tips - Network Topologies

Most common exam questions:

  • "Describe star topology" → All devices connect to central switch. Data goes device → switch → destination.
  • "Advantage of star?" → Easy to add devices / isolated failures (one cable break = one device affected)
  • "Disadvantage of star?" → Central switch = single point of failure (if it dies, ALL devices lose connection)
  • "Describe mesh topology" → Devices connect to multiple/all other devices. Multiple paths for data.
  • "Advantage of mesh?" → No single point of failure / very reliable (data finds alternative paths)
  • "Disadvantage of mesh?" → Very expensive (lots of cables) / complex to manage
  • "Compare star vs mesh" → Star: cheaper, single point of failure. Mesh: expensive, very reliable

Key comparison facts to memorize:

Aspect Star Mesh
Structure Central switch Multiple interconnections
Single Point of Failure? YES (switch) NO (redundant paths)
Cost Moderate Very High
Reliability Moderate Very High
Use Case Homes, offices, schools Critical systems, data centers

Common mistakes to avoid:

  • Confusing "central switch fails = all down" with "one cable fails = all down" - in star, one cable = one device!
  • Saying star has no single point of failure - it does (the switch)!
  • Thinking mesh is used everywhere - it's only used for critical systems due to cost
  • Forgetting bus and ring are largely obsolete - exams focus on star vs mesh
  • Not explaining WHY mesh is reliable (multiple paths for data)

Perfect exam answer structure:

"Compare star and mesh topologies" (4 marks):

Star: All devices connect to central switch (1 mark).
Mesh: Devices connect to multiple other devices (1 mark).
Star has single point of failure (central switch) (1 mark).
Mesh has no single point of failure, data takes alternative paths (1 mark).

Now try it yourself

Quiz · Question 1 of 16

In a star network topology, all devices connect to which central component?

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