Networking - Hub

A hub is a basic networking device that connects multiple computers or other network devices together within a Local Area Network (LAN). It operates at the Physical Layer (Layer 1) of the OSI (Open Systems Interconnection) model. The primary function of a hub is to receive data packets (signals) from one device and broadcast them to all other connected devices in the network.

Although hubs were once commonly used in small networks, they have largely been replaced by more intelligent devices such as switches and routers, which provide better performance, security, and efficiency.

What Is a Hub?

A hub acts as a central connection point for network devices. It contains multiple ports (typically 4, 8, 12, or 24) where devices like computers, printers, and servers can be connected using Ethernet cables.

When a device sends data to the hub, the hub retransmits (broadcasts) that data to all connected devices, regardless of the actual destination. The device that recognizes its own address processes the data, while others ignore it.

For example, if Computer A sends a message to Computer B, the hub sends that same message to all devices (Computers B, C, D, etc.), even though only Computer B needs it.

How a Hub Works

1. Data Transmission:
   A hub receives electrical signals (data) from one of its ports.

2. Broadcasting:
   It amplifies or regenerates the signal and then transmits it to all other ports.

3. Receiving:
   The intended recipient device accepts the data; all others discard it.

Because hubs cannot identify which device should receive the data, they treat all data equally, which leads to network congestion and reduced efficiency in busy networks.

Types of Hubs

There are mainly three types of hubs based on their functionality:

1. Passive Hub:

   • Simply connects devices and allows data signals to pass through without amplification.

   • Does not boost the signal, so the transmission distance is limited.

   • Acts more like a connector or wiring center.

2. Active Hub:

   • Amplifies or regenerates incoming signals before sending them out.

   • Helps extend the distance over which data can travel.

   • Requires a power supply to function.

3. Intelligent (or Smart) Hub:

   • Includes basic management features like monitoring traffic or detecting network issues.

   • Works somewhat like a switch but still operates mainly as a broadcast device.

Advantages of a Hub

• Simple Setup: Easy to install and configure, suitable for small or temporary networks.

• Low Cost: Cheaper than switches or routers, making them budget-friendly for basic networking.

• Useful for Troubleshooting: Can be helpful in testing or diagnosing simple network issues.

Disadvantages of a Hub

• No Traffic Control: Sends data to all devices, leading to unnecessary traffic and reduced efficiency.

• Lack of Security: Since data is broadcast to every device, it’s easier for unauthorized users to intercept it.

• Collision Problems: Multiple devices transmitting at the same time can cause data collisions, slowing down the network.

• Limited Performance: Operates in half-duplex mode, meaning data can only be sent or received at one time, not both.

• Outdated Technology: Hubs are mostly replaced by switches, which are faster and smarter.

Hub vs. Switch

Example Scenario

Imagine an office with four computers connected to a hub. When one computer sends a file to another, the hub sends that data to all four computers. Only the target computer processes the file, but the other three still receive the data. This wastes bandwidth and can slow down performance — which is why modern networks use switches instead.

Conclusion

A hub is a simple networking device that connects multiple computers in a LAN and transmits data by broadcasting it to all connected devices. While it is easy to use and inexpensive, it lacks the intelligence to manage traffic efficiently, leading to congestion and reduced performance. For this reason, hubs have largely been replaced by network switches, which offer faster, more secure, and more efficient communication.