---
title: "Switching and why necessary"
subject: "Computer Networks and Security"
chapter: 2
key: "semester_7/computer_networks_and_security:switching-meaning-necessity"
source: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/switching-meaning-necessity
site: BCT Engineering
---

# Switching and why necessary

Computer Networks and Security · Chapter 2: Physical Layer

- Asked in: 2070 Asar, 2+2 marks
- Video: [Switching Techniques in Computer Networks](https://www.youtube.com/watch?v=-HlJ4psu5aU) — Neso Academy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/switching-meaning-necessity
- Whole chapter: https://www.bctengineer.com/md/semester_7/computer_networks_and_security/chapter-2

## Question

What do you mean by switching in communication? Why is switching necessary?

## Short answer

Switching routes data through intermediate nodes to the correct outgoing line. Necessary because direct links between all pairs require n(n-1)/2 links (4950 for 100 devices), while a switched network needs one link per device; it reduces cost, enables any-to-any communication, and allows sharing of transmission lines.

## Answer

#### Meaning
Switching is the method of connecting source and destination nodes through intermediate network nodes (switches) that forward data from the incoming line to the correct outgoing line. Types are circuit, message and packet switching.

#### Why switching is necessary
- A **direct link between every pair** of n devices needs n(n-1)/2 links. For 100 devices this is 4950 links, which is not practical. A switched network needs only one link per device to a switch.
- It lets **many users share** expensive transmission lines and equipment.
- It allows **any-to-any communication** on a large WAN, such as the telephone system or the Internet.
- It reduces **cost** of cabling and ports and makes the network **scalable**.
- It supports **efficient bandwidth use**, routing around failed links and managing congestion.

## Check yourself

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

1. How many links are needed to connect n devices directly in a full mesh?
   A. n
   B. n(n-1)/2
   C. n^2
   D. 2n
   Answer: B. A full mesh needs n(n-1)/2 links, e.g. 4950 for 100 devices. (Key point: Links needed)

2. How many links does a switched network need per device?
   A. One link to a switch
   B. n-1 links
   C. n(n-1)/2 links
   D. None
   Answer: A. Each device needs only one link to a switch. (Key point: Switched network links)

3. Which is a reason switching is necessary?
   A. It lets many users share expensive lines and enables any-to-any communication
   B. It increases cabling
   C. It removes routing
   D. It stops sharing
   Answer: A. Switching allows sharing, scalability, lower cost and any-to-any communication. (Key point: Why necessary)

## Related in Computer Networks and Security

- [Switching compared with multiplexing](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Aswitching-vs-multiplexing) — Computer Networks and Security, chapter 2
- [Types of data switching](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Atypes-of-switching) — Computer Networks and Security, chapter 2

## Related in other subjects

- [Switching techniques in data communication](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aswitching-techniques-data-comm) — Telecommunications, chapter 8, asked 3×
- [Russell: wisdom more necessary with knowledge](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Arussell-wisdom-more-necessary) — Communication English, chapter 2, asked 2×
- [Define AM; switching modulator for DSB-FC](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Adefine-am-switching-modulator) — Communication Systems, chapter 2
- [Why modulation is necessary](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Amodulation-necessary-channel) — Communication Systems, chapter 1