Ring Topology
Pass a note round a circle of friends, each handing it to the person on their left, until it reaches the one it is for. That is a ring network — and you can already guess what happens if one friend leaves the circle.
1What a ring topology is
Send A → D and watch B and C pass it on. Then cut one cable, or switch off PC C.
2How data travels in a ring
There is no hub. PC A hands its message to PC B. B sees it is not for B, and passes it on to C. C passes it to D, which keeps it. Every computer on the way receives and passes on the data.
Because data only goes one way, a message from A to F has to go the long way — through B, C, D and E — even though F is right next to A on the other side.
3One gap stops it all
Cut any one cable in the lab, or switch off any one computer. Data can no longer get all the way round, and the whole ring stops — every pair drops to zero. This is the ring’s biggest weakness.
4Advantages and disadvantages
- No central hub is needed.
- Every computer gets a fair turn, since data moves one way in order.
- Data does not collide, even when the network is busy.
- Each computer repeats the signal as it passes it on, so data can travel far.
- One broken cable or one failed computer stops the whole network.
- Adding or removing a computer breaks the ring while you do it.
- Data may pass through many computers, which is slow.
- Faults are hard to find.
5Check yourself
In a ring network, PC C is switched off. What happens?
How does data travel in a ring topology?