Mesh Topology
What if every computer had its own private cable to every other computer? Nothing could ever be cut off by one broken cable. The price is the cable — a lot of it.
1What a mesh topology is
Four computers, six cables. Send A → D. Cut the A–D cable and send again. Then cut two of A's three cables.
2Why a mesh almost never fails
The lab uses four computers, so the six cables are easy to count. With everything working, A sends straight down its own cable to D. Cut that cable and A simply sends through another computer instead — B passes it on to D. Cut two of A’s three cables and A still reaches everyone through the last one. There are so many paths that one broken cable changes nothing.
3Counting the cables
Each of the n computers needs a cable to the other n − 1. That counts every cable twice (once from each end), so:
Drag the slider to add computers.
A lab of 40 computers would need 780 cables, and every computer would need 39 ports. That is why whole labs are never wired as a mesh. Meshes are used where failure is not an option and there are only a few important machines — like the main routers that carry the Internet between cities.
4Advantages and disadvantages
- Most reliable: a broken cable does not cut anyone off.
- Data can take the direct cable, so it is fast.
- A private cable for each pair is more secure.
- Faults are easy to pin down to one cable.
- Needs the most cable by far — n × (n − 1) ÷ 2.
- Every computer needs many network ports.
- Very costly and hard to set up.
- Adding one computer means cabling it to all the others.
5Check yourself
How many cables are needed to connect 5 computers in a full mesh?
Which is the main disadvantage of a mesh topology?