One switch fails and the branch shuts
A branch has one switch. A cleaner pulls out its power lead to plug in a vacuum cleaner. Every desk loses the internet, and the card machines stop.
Good design asks, "What if this one part fails?" and plans a spare before it happens.
By the end of this lesson
Note
I can use shape, segmentation, security and spares to make a design that keeps working.
Key words
| Word | What it means |
|---|---|
| Network | computers and devices joined together so they can share data |
| Router | a device that passes messages from one network to another |
| Topology | the shape of a network: how its devices are joined |
| Star topology | every device joins one central device |
| Redundancy | a spare part or spare path that takes over when one fails |
| Single point of failure | one part that, if it fails, stops the whole service |
| Authentication | proving who you are, such as with a password |
| Segmentation | splitting a network into parts so one part cannot freely reach another |
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Starter
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Four principles of a good design
| Principle | The question to ask | An example answer |
|---|---|---|
| Shape (topology) | How are the devices joined? | A star: every desk to a switch, every switch to the router |
| Segmentation | Which groups must be kept apart? | Guests, staff and servers on three separate networks |
| Security | Who may do what, and how do they prove it? | A password and a second check for remote access. Staff cannot reach the finance folder |
| Redundancy | What happens if one part fails? | A second link to the internet and a spare switch |
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Check
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3 questionsHave a go: your answers are marked here and then forgotten. Sign in if you would like your score kept, and to pick up where you left off.Sign in to keep your score
Your answers are marked here and are not kept. A college account keeps every student’s marks.