---
title: "Datagram vs virtual circuit switching"
subject: "Telecommunications"
chapter: 8
key: "semester_8/telecommunications:datagram-vs-virtual-circuit"
source: https://www.bctengineer.com/q/semester_8/telecommunications/datagram-vs-virtual-circuit
site: BCT Engineering
---

# Datagram vs virtual circuit switching

Telecommunications · Chapter 8: Data Communication

- Asked in: 2076 Asoj, 2 marks
- Video: [Lec-19: Datagram Switching Vs Virtual Circuit Switching in Packet Switching | Computer Networks](https://www.youtube.com/watch?v=-S-NThI_79o) — Gate Smashers
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/telecommunications/datagram-vs-virtual-circuit
- Whole chapter: https://www.bctengineer.com/md/semester_8/telecommunications/chapter-8

## Question

Differentiate between datagram switching and virtual circuit switching.

## Short answer

Datagram switching routes each packet independently with full address, so packets may arrive out of order. Virtual circuit switching sets up a logical path first, uses a short VC number, and all packets follow the same route in order. Examples: IP versus X.25, Frame Relay, ATM.

## Answer

Both are packet-switching methods. In **datagram switching** each packet is routed independently; in **virtual circuit switching** a logical path is set up first and all packets follow it.

| Point | Datagram | Virtual circuit |
|---|---|---|
| Set-up phase | None | Call set-up and release needed |
| Addressing | Full address in every packet | Short VC number |
| Route | Each packet may take a different path | All packets on the same path |
| Packet order | May arrive out of order | Arrive in order |
| Router failure | Only lost packets affected | All VCs through it fail |
| Examples | IP (Internet) | X.25, Frame Relay, ATM |

## Check yourself

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

1. Which needs a call set-up and release phase?
   A. Virtual circuit
   B. Datagram
   C. Neither
   D. Both
   Answer: A. Datagram has none; a virtual circuit sets up a logical path first. (Key point: Set-up phase)

2. What does each packet carry in a virtual circuit network versus datagram?
   A. Full address in VC, short number in datagram
   B. Full address in both
   C. Short VC number in VC, full address in datagram
   D. No address in either
   Answer: C. VC uses a short identifier; datagram packets carry the full destination address. (Key point: Addressing)

3. What is the effect of a router failure?
   A. Same in both
   B. No effect in either
   C. In datagram all connections fail; in VC only lost packets
   D. In datagram only lost packets are affected; in VC all VCs through it fail
   Answer: D. Datagram packets can be rerouted; a VC depends on its fixed path. (Key point: Router failure)

## Related in Telecommunications

- [Short note: Virtual-circuit network](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Ashort-note-virtual-circuit) — Telecommunications, chapter 8, asked 2×
- [Digital vs manual switching; evolution in Nepal](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Adigital-vs-manual-nepal-evolution) — Telecommunications, chapter 1
- [Multistage switching; TST vs STS](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Amultistage-tst-sts-compare) — Telecommunications, chapter 4
- [Circuit switch vs packet switch](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Acircuit-vs-packet-switch) — Telecommunications, chapter 8
- [Marconi transmitter, mobile vs nomadic, Telecom Act](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Amarconi-mobile-nomadic-act) — Telecommunications, chapter 1
- [TST vs STS and three-stage design](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Atst-sts-design-crosspoints) — Telecommunications, chapter 4

## Related in other subjects

- [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×
- [Virtual circuit switching](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Avirtual-circuit-switching) — Computer Networks and Security, chapter 2
- [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 vs packet switching](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Acircuit-vs-packet-switching) — Data Communication, chapter 7, asked 4×