Switching Explained

How Network Switches Move Data

Inside homes, offices and data centers, most communication does not go directly to the internet. It happens within local networks. Network switches are the devices that make this internal communication fast and efficient.

Switching is about moving data between devices on the same network. It works at a lower level than routing and focuses on MAC addresses rather than IP addresses.

This article explains what switching is, how switches work and why they are essential.

What is switching

Switching is the process of forwarding data frames between devices within the same local network.

A switch connects multiple devices such as:

• Computers

• Phones

• Printers

• Servers

• Access points

Its job is simple. When a frame arrives, the switch decides which port should receive it and forwards it there.

Why switches exist

Early networks used hubs. Hubs sent every packet to every device. This caused congestion and security issues.

Switches improved this by:

• Sending data only where it needs to go

• Reducing unnecessary traffic

• Increasing performance

• Improving privacy

Switches made modern local networks possible.

Switch vs hub

Hub

• Broadcasts data to all ports

• No intelligence

• Slow

• Insecure

Switch

• Learns device locations

• Sends data only to destination

• Fast

• Efficient

Hubs are now obsolete. Switches are everywhere.

How a switch works step by step

Switches operate using MAC addresses.

Step 1. Frame arrives at a port

A device sends an Ethernet frame to the switch.

Step 2. Switch reads source MAC

The switch notes which port the source MAC address came from.

Step 3. Switch updates MAC table

The switch builds a table that maps MAC addresses to ports.

Step 4. Switch checks destination MAC

If the destination MAC is known, the frame is sent only to that port.

Step 5. If destination is unknown

The switch floods the frame to all ports except the incoming one.

Once the destination replies, the switch learns its MAC address and updates the table.

MAC address table explained

The MAC address table is the switch’s memory.

It stores:

• MAC address

• Associated port

• Timestamp

Entries expire if the device is inactive. This keeps the table accurate.

What happens during broadcast traffic

• Some traffic must reach all devices.

Examples:

• ARP requests

DHCP discovery

Switches broadcast these frames to all ports in the same network segment.

This is normal and necessary.

Broadcast domains

A broadcast domain is a group of devices that receive broadcast traffic.

By default:

• One switch equals one broadcast domain

Large networks use VLANs or routers to split broadcast domains and reduce noise.

Switching and performance

Switches improve performance by:

• Reducing collisions

• Supporting full duplex communication

• Allowing multiple conversations simultaneously

Each port is its own collision domain. This means devices do not interfere with each other.

Switching vs routing

This is a common confusion.

Switching

• Uses MAC addresses

• Works within a local network

• Fast and hardware optimized

Routing

• Uses IP addresses

• Connects different networks

• Makes path decisions

Switching handles local delivery. Routing handles inter network delivery.

VLANs and switching

VLANs allow one physical switch to act like multiple logical networks.

Benefits:

• Traffic isolation

• Improved security

• Reduced broadcast traffic

Better organization

Devices in different VLANs cannot talk directly without a router.

Switch security basics

Switches support basic security features such as:

• Port security

• MAC address limits

• Disabling unused ports

These features prevent unauthorized devices from connecting.

Common misconceptions

Misconception 1

Switches use IP addresses. No. They use MAC addresses.

Misconception 2

Switches connect to the internet. No. Routers do that.

Misconception 3

All switches are smart. Unmanaged switches are simple. Managed switches provide advanced control.

Conclusion

Switching is the foundation of local networking. Switches intelligently forward frames using MAC addresses and make communication efficient and fast. Without switches, modern networks would be noisy, slow and insecure. Understanding switching prepares you perfectly for routing, VLANs and network segmentation.