Quick definition: A computer network hub is a Layer 1 connected device that retransmits the received data to all of its ports. Unlike network switches, computer network hubs do not break conflict domains.

Sometimes, studying for an IT certification requires learning a technology that is rarely seen in the real world, and for many IT professionals, a computer network hub fits that description.

While network hubs are not common in modern web design, they still appear in some exams. Still, there are some computer network hubs. Understanding them helps you understand important fundamental networking topics such as collision domains, Layer 1 connectivity, and full-duplex vs. half-duplex. With that in mind, let's take a closer look at computer networking hubs!

What is a Computer Network Hub?

Computer network hubs are Layer 1 network devices that are no longer common in modern networks, but are still occasionally found in legacy systems and network exams. For most modern use cases that may require a network hub, a Layer 2 switch, port mirroring, or network tap is often a better choice.

Hubs are standard for 10Mbps 10BASE-T networks, and devices are typically connected to computer network hubs using Ethernet cables with RJ45 connectors. However, technically, it can use different connection media, so the RJ45 connection is not necessary for the device to act as a hub.

One of the most important defining characteristics of a hub is what it doesn't do.

Hubs don't protect against network collisions because a single hub provides only a single collision domain. Understanding the importance of this is probably the most important reason for aspiring networking professionals to learn computer networking hubs.

Computer Network Hubs vs. Network Switches: Why Collision Domains Matter

Network hubs are no longer used often because network switches can handle most use cases and break down collision domains.

A collision domain is a network segment where data transmissions may collide on a network medium, such as cables, and need to be retransmitted. These retransmissions can cause congestion and latency on the network.

In the past, cost was a reason to use a hub, but today the cost of an unmanaged switch is low enough that it is no longer a decision-making factor.

What are the 3 most common types of computer network hubs?

In the What is a network hub? On this issue, I have only labeled two of them as technically correct. There are three common types of computer network hubs that you will see online. They are:

Passive: These hubs do not amplify the network signal and retransmit data to all ports.

Active: In addition to retransmitting data to all ports, an active network hub can also act as a signal booster, extending the Ethernet signal.

Intelligent: Most descriptions of "smart" hubs are actually descriptions of other network devices. In general, a hub is described as a smart hub if it has additional switching, management, or monitoring capabilities.

What are the functions of a computer network hub?

A computer network hub has two main functions: receiving and transmitting network data through all of its ports. For active hubs, computer network hubs can also act as signal boosters. Let's take a closer look at these three features.

Rx: Receive data, Tx: Send data

The basic functions of a hub in a network are:

● The hub receives data from connected devices

● The hub transmits data to all connected devices

● Since the hub can only send or receive at a time, it operates in a half-duplex mode

All of this Tx and Rx stuff might confuse aspiring web professionals, but once you understand what they mean, everything is pretty straightforward. They are just shorthand for Transmit (Tx) and Receive (Rx).

In networks, physical connections are often made through cables and connectors (wireless connections are a notable exception). These connections are typically used for one purpose per wire or "pin".

In 10BASE-T network communication, the host uses pins 1 and 2 to transmit data and pins 3 and 6 to receive data. Therefore, pins 1 and 2 are "Tx" and 3 and 6 are "Rx". Connected devices such as hubs exchange Tx and Rx by using 1 and 2 receives and 3 and 6 sends.

Today, automatic MDI-X detection on network interfaces makes these things less important in practice. But in the age of network hubs, technicians are often busy looking for crossover cables to cope with different port pinouts.

Enhance the signal

Sometimes, a signal is needed to travel farther. Just like a WiFi extender can boost a wireless signal, an active network hub can act as a repeater for a wired connection. Active computer network hubs are a possible solution to a problem with weak signal strength or extending the cable beyond 100 meters (the typical maximum length of a twisted pair cable Ethernet).

Are there any modern use cases for network hubs?

Nowadays, computer network hubs have become practically a traditional technology. In a few cases, a hub can be helpful.

For example, some IT professionals buy network hubs when they want to broadcast traffic to multiple Ethernet ports so that they can easily sniff traffic from other systems using tools like Wireshark. However, a network tap or switch that supports port mirroring may be a better solution for a production environment.

Additionally, because computer network hubs are not full-duplex and do not support modern network speeds, introducing them into the network can create performance issues.

Similarly, a hub may be a quick way to connect devices for troubleshooting or replacing a broken switch, but a standard network switch may be better.

How to set up a computer network hub

The setup process for a computer network hub is similar to that of an unmanaged Layer 2 switch. While the specifics may vary from model to model, the general process is as follows:

Plug the hub into a power source if needed: Hubs, especially active hubs that need to amplify signals, typically need to be powered by an AC power cord, wall power adapter, or similar power connector.

Connect network devices to network ports: In the era of 10BASE-T connectivity, hubs are very popular. An RJ45 connector may be used to connect an Ethernet cable.

Connect the device to the uplink port: On modern networks, this step may not be required, but it may occur. Some hubs include an "uplink" port to connect to another hub. Uplink ports are implemented in a number of different ways, including the use of pins that are already "crossed" to avoid crossover cables that need to switch between transmission (Tx) and receive (Rx) pins.

Check connectivity: At this point, the network devices should be able to communicate. Most hubs have diagnostic LEDs that can help confirm status such as power, collisions, and port activity.

How to fix network hub issues

Some network hub-related issues are easy to diagnose, while others are a little more complicated. Let's see how to troubleshoot different network hub issues.

No power supply

If the network hub doesn't turn on at all, there's a good chance there's a problem with the power supply. Make sure the wall outlet is powered and securely connected. If you have a spare power cord, replace it for testing.

There is electricity, but there is no connection

If the hub is powered on but the connected device isn't receiving a network connection, there may be some issues. To begin troubleshooting, make sure that all cables are securely connected. Then, use the following troubleshooting steps to narrow down the issue:

● Confirm that the device is properly configured with network settings

● Check that the correct cable is being used (e.g., crossover cable vs. straight-through cable)

● Check if all devices support the hub's network speed (e.g. 10Mbps half-duplex)

Network performance issues

If adding a network hub is causing issues such as latency, jitter, and reduced network throughput, one of the quickest troubleshooting steps may be to add an unmanaged switch. If this method solves the problem, the root cause may be an increase in conflicts on the network.

In the past, it was wise to examine the network architecture and see if design practices such as the 5-4-3 rule helped. Nowadays, however, installing a network switch can be a faster and better way to solve the problem.

summary

Whether you're studying for your next certificate, trying to figure out how old equipment found in a wiring closet works, or just interested in reinforcing your networking fundamentals, knowing a computer network hub can help.

While this legacy technique may not be the first choice for the modern shopping list of the web, it is still useful in some special situations and worth learning.