Circuit vs Packet Switching
“Write two points of difference between circuit switching and packet switching” is one of the most repeated 2-mark questions in this unit. Watch the difference first, then learn the points.
1The same three conversations, both ways
A, C and E all start talking to B, D and F at the same moment. Run it with circuit switching, then with packet switching.
Choose a technique and press Start. Then try the other one. Drag sideways to turn.
Circuit switching connects two calls and refuses the third, because each connected call holds a whole route. Packet switching gets all three messages through the very same network, because every link is shared.
2The differences
| Circuit switching | Packet switching | |
|---|---|---|
| Path | A dedicated path is set up before communication starts | No dedicated path; nothing is set up in advance |
| How data is sent | As one continuous stream along the path | Broken into packets, each sent independently |
| Route | All data follows the same path | Packets may take different routes |
| Order of arrival | Data arrives in order | Packets may arrive out of order and are reassembled |
| Sharing | The path is reserved, even when nothing is sent | Links are shared by many users at once |
| Store and forward | Not used | Used at every switch |
| If a link fails | The communication is cut off | Packets go by another route |
| Example | Traditional landline telephone call | The Internet |
3From the board papers
▶Show the answer
- In circuit switching, a dedicated path is set up between sender and receiver before communication starts. In packet switching, no dedicated path is set up.
- In circuit switching, all data follows the same path. In packet switching, data is broken into packets that are sent independently and may take different routes.
4Circuit or packet?
Read the statement and pick the technique it describes.
5Check yourself
Which switching technique does the Internet use?
Which statement is true of circuit switching but NOT of packet switching?