What Is a Hub? Functions, Types, How It Works and Hub vs Switch

A hub is a basic networking device that connects multiple devices within a local network. When a hub receives data from one connected device, it repeats that data to all other connected ports instead of identifying the specific destination device.

Hubs were commonly used in older Ethernet networks. However, modern networks generally use switches because switches can forward traffic more efficiently. Understanding hubs is still useful because they explain how early Ethernet networks handled communication.

For a broader introduction to networking hardware, see Network Devices Explained.

How Does a Network Hub Work?

A hub works at the Physical Layer of the OSI model. It does not examine MAC addresses or make intelligent forwarding decisions.

When a device sends an electrical or optical signal to a hub, the hub receives that signal and repeats it through its other ports. As a result, every connected device can receive the transmitted signal, even though only one device may be the intended destination.

For example, imagine four computers connected to a hub. If Computer A sends data to Computer B, the hub repeats the signal toward Computers B, C, and D. Computer B processes the relevant data, while the other computers ignore traffic that is not intended for them.

What Does a Hub Do?

A hub performs a relatively simple function compared with modern networking devices.

Connects Multiple Devices

The primary purpose of a hub is to connect multiple network devices together. Computers and other Ethernet devices can connect through the hub’s physical ports.

Repeats Signals

A hub receives an incoming signal and repeats it across its other ports. It does not determine which device should receive the data.

Extends a Physical Network

A hub can provide additional physical connections for devices within a local network. However, it does not provide the advanced traffic management capabilities available in modern switches.

Operates at the Physical Layer

A traditional hub operates at Layer 1, the Physical Layer of the OSI model. It deals with signals and physical transmission rather than MAC addresses or IP addresses.

Types of Network Hubs

Network hubs can be classified into several types based on how they handle signals and power.

Passive Hub

A passive hub mainly provides a physical connection between network devices. It does not actively regenerate or strengthen the signal.

Active Hub

An active hub receives signals, regenerates them, and then retransmits them through its ports. Because it actively processes the physical signal, it can help maintain signal quality within its supported range.

Intelligent Hub

An intelligent hub provides additional management capabilities compared with a basic hub. However, these devices are largely outdated because modern switches provide much more advanced network management features.

What Is a Hub Port?

A hub contains multiple physical ports that allow devices to connect to the network.

For example, older Ethernet hubs could have:

• 4 ports
• 8 ports
• 12 ports
• 16 ports
• 24 ports

Each connected device shares the same network environment provided by the hub.

The number of ports determines how many devices can directly connect to the hub. However, using more ports also means more devices share the available network resources.

Hub and Collision Domains

One of the major limitations of hubs is their shared collision domain.

When multiple devices connected to a hub transmit at the same time, their signals can interfere with each other. This creates an Ethernet collision.

The devices must then wait and retransmit their data according to the network’s Ethernet access mechanism.

As the number of active devices increases, the likelihood of collisions can increase as well. This makes hub-based networks less efficient than modern switched Ethernet networks.

Hub vs Network Switch

A hub and a switch can both connect multiple devices, but they handle traffic differently.

A hub sends incoming signals to its other ports. A switch, on the other hand, can learn MAC addresses and forward known unicast frames toward the appropriate port.

For a detailed explanation of modern switching, see What Is a Network Switch?.

Hub vs Router

A hub and router serve completely different purposes.

A hub connects devices within the same physical network segment. A router connects different IP networks and forwards packets between those networks.

For example:

Computers → Hub → Router → Internet

The hub provides basic physical connectivity, while the router handles communication between different networks.

A router can make decisions using IP addressing and routing information. A hub does not perform these functions.

Hub and MAC Addresses

A traditional hub does not use MAC addresses to decide where traffic should go. It simply repeats the received signal.

This is one of the main differences between a hub and a switch.

A switch can learn MAC addresses and associate them with specific ports. As a result, it can make forwarding decisions based on the destination MAC address.

A hub does not have this capability because it operates at the Physical Layer.

Hub and Network Communication

A hub provides basic physical connectivity between devices, allowing signals to travel across a local network.

For example, when one computer sends data through a hub, the hub repeats the signal to its other ports. The connected devices receive the signal and determine whether the transmitted data is relevant to them.

This is a basic example of how devices can exchange information across a network. For a broader explanation of network communication, see Network Communication Basics.

Advantages of Network Hubs

Although hubs are outdated, they have some simple characteristics that made them useful in earlier networks.

Simple Operation

Hubs do not require complex configuration. Devices can usually be connected directly through Ethernet cables.

Low Complexity

Because hubs do not maintain MAC address tables or perform advanced forwarding, their operation is relatively simple.

Easy to Understand

Hubs provide a straightforward example of how physical network signals can be distributed between multiple devices.

Limitations of Network Hubs

The limitations of hubs are the main reason switches replaced them in modern Ethernet networks.

Unnecessary Traffic

A hub repeats incoming traffic across its other ports. This creates unnecessary traffic because devices receive signals that may not be intended for them.

Collisions

All connected devices share the same collision domain. Simultaneous transmissions can therefore result in collisions.

Lower Performance

As more devices transmit data, network efficiency can decrease. Shared bandwidth and collisions can limit overall performance.

No MAC-Based Forwarding

A hub cannot examine destination MAC addresses and select a specific output port.

No Advanced Management

Modern switches can provide features such as VLANs, traffic controls, monitoring, and security options. A basic hub does not provide these capabilities.

Are Network Hubs Still Used?

Network hubs are rarely used in modern computer networks. Ethernet switches have largely replaced them because switches provide better performance, better traffic management, and more efficient forwarding.

However, hubs can still appear in educational environments or legacy network equipment. They can also be useful when studying the fundamentals of Ethernet communication.

For most practical network deployments, a switch is the more appropriate choice.

How Does This Affect Network Performance?

A hub can reduce network performance because all connected devices share the same collision domain and transmission environment.

When several devices communicate simultaneously, collisions can occur. Devices may then need to retransmit their data, which can reduce efficiency.

A switch avoids many of these limitations by creating separate collision domains for its ports and forwarding frames based on learned MAC addresses.

Therefore, replacing an old hub with a modern switch can significantly improve a local Ethernet network.

Why Are Hubs Important to Learn?

Although hubs are no longer common, they are useful for understanding the development of Ethernet networking.

A hub demonstrates the basic idea of repeating physical signals between connected devices. It also provides a useful comparison with switches, which introduced more intelligent frame forwarding.

Understanding this difference makes it easier to learn how modern network devices handle communication.