Circuit switching and packet switching
| English | Chinese | Pinyin |
|---|---|---|
| packet switching | 分组交换 | fēn zǔ jiāo huàn |
| circuit switching | 电路交换 | diàn lù jiāo huàn |
| dedicated path | 专用路径 | zhuān yòng lù jìng |
| sequence number | 序列号 | xù liè hào |
| latency | 延迟 | yán chí |
Circuit vs packet switching 分组交换
- There are two ways to move data across a network.
- Circuit switching 电路交换 reserves a path; packet switching sends independent packets.
- The modern internet uses packet switching.
Circuit switching
- A dedicated path 专用路径 is set up between the two ends before any data is sent, reserved for the whole conversation, then released.
- Pros: reserved bandwidth and in-order delivery.
- Cons: inefficient during silences (the line is idle but reserved) and slow to set up.
- Classic example: the traditional telephone network.
Circuit switching: one dedicated path is reserved end to end
Packet switching: packets travel independently and may take different routes
In circuit switching:
Circuit switching reserves one path end-to-end (reserved bandwidth) — but it wastes the line during silences.
Packet switching
- The data is split into packets, each sent independently with the destination address and a sequence number 序列号.
- Routers make a per-packet decision, so packets may take different routes and arrive out of order; the destination reassembles them by sequence number.
- Pros: efficient (a link is shared by many conversations) and robust (reroute around failures). Cons: variable latency 延迟 and possible loss (TCP handles reliability).
A home Wi-Fi router: it forwards packets between your devices and the internet
A packet's journey across the internet
Step through packet switching. The message is split up, each packet finds its own way, and the destination puts them back together — which is why the internet is so efficient and hard to break.
Match each term to what it means.
Circuit = one reserved path; packet = independent packets reordered by sequence number — what the internet uses.
A key advantage of packet switching is that it is:
Sharing links is efficient and rerouting makes it resilient. The trade-off is variable latency and possible loss (TCP fixes that).
Because each packet carries a sequence number, the destination can reassemble the message in the right order and re-request any missing packet.
Packets may arrive out of order or be lost; the sequence numbers (and TCP) put everything right.
Comparison
| Aspect | Circuit switching | Packet switching |
|---|---|---|
| Path | dedicated, reserved | shared, per-packet |
| Setup | slow | none |
| Bandwidth use | inefficient | efficient |
| On failure | the circuit is cut | reroute around it |
| Suits | constant voice flows | bursty web/email |
A network switch connects many wired devices on a local network
The modern internet uses:
The internet uses packet switching for its efficiency and resilience.
You've got it
- circuit switching reserves a dedicated path (reserved bandwidth, but wasteful + slow setup)
- packet switching sends independent packets that may take different routes
- packets carry sequence numbers so the destination can reassemble them in order
- the internet uses packet switching — efficient and robust