---
title: "Circuit vs packet switching"
subject: "Data Communication"
chapter: 7
key: "semester_5/data_communication:circuit-vs-packet-switching"
source: https://www.bctengineer.com/q/semester_5/data_communication/circuit-vs-packet-switching
site: BCT Engineering
---

# Circuit vs packet switching

Data Communication · Chapter 7: Switching

- Asked in: 2074 Asoj, 2+5 marks; 2072 Chaitra, 6 marks; 2070 Asar, 2 marks; 2068 Chaitra, 5 marks (asked 4 times)
- Video: [Circuit Switching vs Packet Switching](https://www.youtube.com/watch?v=G7n8thqwO2c) — PowerCert Animated Videos
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/circuit-vs-packet-switching
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-7

## Question

Compare circuit switching with packet switching.

## Short answer

Circuit switching establishes a dedicated path before transmission with setup, transfer, and teardown phases; bandwidth is reserved but can be wasted. Packet switching breaks data into packets that are store-and-forward routed independently, sharing links on demand with variable queuing delay. Circuit switching suits voice, packet switching is efficient for bursty data like Internet.

## Answer

**Switching** is the method of moving data from a source to a destination through intermediate nodes of a network. In **circuit switching** a dedicated end-to-end path is set up before data transfer. In **packet switching** the message is split into packets which are routed independently through the network and share links.

```text
 Circuit: A ==[sw]==[sw]==[sw]== B   (dedicated path, setup/teardown)
 Packet : A --> [R]-->[R]--> B       (store and forward, packets may
              \--> [R] -->/          take different routes)
```

| Point | Circuit switching | Packet switching |
|---|---|---|
| Path | Dedicated path set up first | No dedicated path |
| Phases | Setup, transfer, teardown | No setup (datagram) or virtual circuit setup |
| Bandwidth | Reserved; wasted when idle | Shared, used on demand |
| Delay | Setup delay, then constant, small | Variable queuing delay at nodes |
| Data unit | Continuous stream | Small packets with header |
| Store and forward | No | Yes |
| Congestion | Blocking at call setup; no congestion later | Possible during transfer; packets may be dropped |
| Failure | Call is dropped | Packets re-routed |
| Efficiency | Poor for bursty data | High for bursty data |
| Charging | By time | By data volume |
| Example | PSTN telephone | Internet, X.25, frame relay |

Circuit switching suits real-time voice; packet switching suits data traffic.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the main path difference?
   A. Packet switching sets up a dedicated path
   B. Circuit switching sets up a dedicated end-to-end path before transfer
   C. Both reserve a path
   D. Neither uses a path
   Answer: B. Circuit switching reserves a path; packet switching shares links. (Key point: Path)

2. Why is circuit switching inefficient for bursty data?
   A. Packets are dropped
   B. Bandwidth is reserved and wasted when idle
   C. It uses store and forward
   D. Headers are large
   Answer: B. Reserved bandwidth is wasted during idle periods. (Key point: Bandwidth use)

3. How does delay differ?
   A. Circuit: setup delay then constant; packet: variable queuing delay
   B. Circuit: variable; packet: constant
   C. Both constant
   D. Circuit has queuing delay at nodes
   Answer: A. Circuit switching has setup delay, then constant small delay; packets queue at nodes. (Key point: Delay)

4. What happens on a node failure?
   A. Circuit call is dropped; packets are re-routed
   B. Both are re-routed
   C. Packets are lost and calls re-routed
   D. Nothing in either
   Answer: A. A circuit call is lost whereas packets can be re-routed. (Key point: Failure)

## Related in Data Communication

- [Switching, circuit vs packet, X.25 layers](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aswitching-define-compare-x25-layers) — Data Communication, chapter 7
- [Packet vs message switching](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Apacket-vs-message-switching) — Data Communication, chapter 7
- [Datagram vs virtual circuit switching](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Adatagram-vs-virtual-circuit) — Data Communication, chapter 7, asked 3×
- [Packet switching](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Apacket-switching-explain) — Data Communication, chapter 7, asked 3×

## Related in other subjects

- [Circuit vs packet switching](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Acircuit-vs-packet-switching) — Computer Networks and Security, chapter 2, asked 3×
- [Circuit switch vs packet switch](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Acircuit-vs-packet-switch) — Telecommunications, chapter 8
- [Datagram vs virtual circuit switching](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Adatagram-vs-virtual-circuit) — Telecommunications, chapter 8
- [IPv6 migration; IPv4 vs IPv6 packet structure](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aipv6-migration-router-packet) — Internet and Intranet, chapter 2