Bus, ring and mesh topologies

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Quick Questions

Shade in the A or B circle for each question.

1. In a bus topology, how do the devices connect?

A Each device has its own cable to a central switch

B They all share one main cable

2. In a ring topology, how does data travel?

A Straight from the sender to every other device at once

B Around a loop from device to device

3. Which topology is the most likely to stop working completely if its one main cable breaks?

A Bus

B Full mesh

4. Which statement describes a full mesh?

A Every device is linked directly to every other device

B Only some devices are linked directly to each other

5. Which is a disadvantage of a full mesh topology?

A It needs many cables and connections, so it is expensive

B It has a single point of failure on the main cable

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1bus topology		Afull mesh topology
2ring topology		Bpartial mesh topology
3A full mesh links every device directly to every other device, giving many alternative paths		CThe shared backbone cable is a single point of failure, so a break can cut off many or all devices, not just one
4A partial mesh links only some devices by multiple paths, which costs less than a full mesh		DMesh has many paths between devices, so data can be rerouted and it avoids a single point of failure
5Bus topology: if one cable breaks, only that device is affected		EAll devices share one main cable, so a break in that cable can stop the whole network
6Mesh topology: has a single point of failure, so it is the least reliable layout		FEach device connects to two neighbours and data travels around a closed loop

Definitions

topology

Fill in the Blanks

Complete each line of code by filling in the missing parts.

busCables = _

if cableOk == _____: print("Bus down")

nextDevice = (i + 1) _ n

fullLinks = n * (n - _) / 2

partialMesh = links _ fullLinks

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A topology = bus

B all devices share one cable

C weak point: any one device

Question 2

A topology = ring

B devices form a loop

C data goes via a central hub

D one break can stop the ring

Question 3

A topology = mesh

B links = one shared cable

C if one link fails, reroute

Question 4

A n = 5

B full_mesh_links = n*(n-1)/2

C partial mesh uses fewer links

D full mesh for 5 devices = 20

Question 5

A topology = bus

B advantage: cheap to install

C disadvantage: needs most cable

Answer Key

Bus, ring and mesh topologies

Section A: Quick Questions

B — They all share one main cable

B — Around a loop from device to device

A — Bus

A — Every device is linked directly to every other device

A — It needs many cables and connections, so it is expensive

Section B: Match the Pairs

bus topology → All devices share one main cable, so a break in that cable can stop the whole network

ring topology → Each device connects to two neighbours and data travels around a closed loop

A full mesh links every device directly to every other device, giving many alternative paths → full mesh topology

A partial mesh links only some devices by multiple paths, which costs less than a full mesh → partial mesh topology

Bus topology: if one cable breaks, only that device is affected → The shared backbone cable is a single point of failure, so a break can cut off many or all devices, not just one

Mesh topology: has a single point of failure, so it is the least reliable layout → Mesh has many paths between devices, so data can be rerouted and it avoids a single point of failure

Section C: Definitions

topology — The layout of a network: bus shares one cable, ring passes data around a loop, and mesh links devices by many paths.

Section D: Fill in the Blanks

busCables = 1

if cableOk == False: print("Bus down")

nextDevice = (i + 1) % n

fullLinks = n * (n - 1) / 2

partialMesh = links < fullLinks

Section E: Spot the Error

C — In a bus topology the single shared cable is the single point of failure. One failed device does not stop the others. The line should read: weak point: the one cable.

C — In a ring, data is passed from each device to the next device around the loop. There is no central hub. The line should read: data passes to next device.

B — A mesh links devices by many paths. One shared cable describes a bus. The line should read: links = many paths.

D — A full mesh of 5 devices needs 5*4/2 = 10 links, not 20. The line should read: full mesh for 5 devices = 10.

C — A bus uses little cable, which is its advantage. Its disadvantage is that collisions increase as more devices share the cable. Needing the most cable describes a full mesh. The line should read: disadvantage: collisions grow.