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What’s a Hub?

An Ethernet hub is a basic network device that receives incoming signals on one port and broadcasts them out to all other connected ports. Understanding how hubs work provides a foundation for grasping core Ethernet communication principles.

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About this video

An Ethernet hub is a foundational network device that connects multiple devices through Ethernet cables, with each cable locking into a numbered port on the unit. The defining characteristic of a hub is its broadcast behavior: when any connected device sends a signal, the hub forwards that signal out through every other port simultaneously, regardless of which device the traffic is intended for. All devices on the hub receive every transmission, even those not addressed to them. This broadcast model was how early Ethernet networks functioned, and while it introduced limitations around efficiency and security, it reflects the original design of the technology. Today, hubs have been largely replaced by switches, which are more intelligent devices capable of directing traffic only to its intended destination. However, studying hub behavior remains a practical way to build a clear mental model of how Ethernet communication works at its core, making it a useful reference point before moving into more advanced networking concepts.

What you'll learn

What's covered

Ethernet Hubs

Aligned to

CompTIA Network+
1.2 Compare and contrast networking appliances, applications, and functions.
CompTIA A+ Core 1
2.2 Compare and contrast common networking hardware.
Cisco CCNA
1.1 Explain the role and function of network components
Cisco CCST Networking
4.5 Explain basic switching concepts

Key terms

Ethernet
A widely used wired networking technology that transmits data over copper cable using electrical signals.
Hub
A basic Layer 1 network device that receives a signal on one port and repeats it out every other port simultaneously, creating a single shared collision domain among all connected devices. Hubs have been replaced by switches in modern networks because they waste bandwidth and cause collisions.
Broadcast
A transmission type in which one device sends a single packet that is delivered to every other device on the local network segment simultaneously. Broadcast traffic is contained within a broadcast domain and does not cross router boundaries.
Port
A logical endpoint for communication in a network, identified by a number that specifies a particular service or application.
Collision Domain
A network segment where data packets can collide with each other when transmitted simultaneously.
Switch
A network device that connects devices within a LAN and forwards traffic based on MAC addresses.

Transcript

What a hub looks like

Here's an example of an eight port hub. Full disclosure, technically this is actually a switch, and there is a difference between a switch and a hub, but go with me on this, because this really looks just like what a hub would look like. What I would do is take my Ethernet cable and plug it into here until I heard a click, and there I know now it's seated. Now I connect all my devices using this hub.

Throughout this module, we're going to be mainly talking about an Ethernet hub. There are different types of hubs that are out there, but Ethernet is the one that we're going to talk about.

I'm going to put a disclaimer out there: we don't really use Ethernet hubs all that often anymore. There are a few use case scenarios where we might want to install a hub, but for the most part we use switches for everything that we want to do, and there's reasoning behind that. However, I'm going to use an example of a hub for the main purpose that it's going to describe the technology of Ethernet. Hubs are what we had when it was originally created, so we can better understand Ethernet and computer communication by first understanding what a hub is.

How a hub operates

Let's say one device wants to talk to another device on this network. What happens is it sends a signal across its Ethernet cable. It comes into the hub on whatever port it's on; let's just say this is port one. Then what this hub will do is broadcast it out all other ports, just like that. And then this computer, along with the other computers, will receive that message.

So that's how a hub operates. Whatever comes into a hub, it will then broadcast out all other ports on that hub.

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