HUB in Computer Networking

In computer networking, a hub is a basic device used to connect multiple computers or network devices together in a local area network (LAN). It operates at Layer 1 (Physical Layer) of the OSI model.

Key Features of a Hub

  • Broadcasts Data: When a hub receives a data packet from one device, it broadcasts (sends) it to all other connected devices, regardless of the destination. This can lead to unnecessary network traffic.

  • No Filtering or Intelligence: Hubs don’t filter data or know the destination of data packets. They’re not aware of MAC addresses and don’t make routing decisions.

  • Half-Duplex Communication: Devices connected to a hub can either send or receive data at a time, not both simultaneously, which can lead to collisions.

  • Collision Domain: All devices connected to a hub share the same collision domain, meaning if two devices send data at the same time, a collision can occur.

Types of Hubs

  • Passive Hub: Simply connects cables and allows signal to pass through without amplification.
  • Active Hub: Amplifies the signal before broadcasting it, helping extend the distance the data can travel.
  • Smart Hub: Has basic management features like monitoring traffic, though still not as advanced as a switch.

Hub vs. Switch

  • Hub: Broadcasts to all ports; less efficient; works at Layer 1.
  • Switch: Sends data only to the intended device based on MAC address; more efficient; works at Layer 2.

HUB Example

Suppose a hub connects 5 computers (PCs): PC1, PC2, PC3, PC4, and PC5 in a local network. When PC1 sends data to PC3, the hub receives the data and broadcasts it to all five PCs. PC3 accepts the data, while PC2, PC4, and PC5 receive it but ignore it. Since hubs don’t filter traffic, all devices share the same network bandwidth. This can cause data collisions and slow performance when multiple PCs try to communicate at once.

Today’s Use

Hubs are mostly outdated in modern networks and have been largely replaced by switches due to their improved performance and efficiency.

Advantages of a Hub

  • Simple to Use: Very easy to set up and operate with no configuration needed.
  • Low Cost: Cheaper than switches and routers.
  • Basic Connectivity: Allows multiple devices to communicate in a local network.
  • Good for Small Networks: Works well in very simple or temporary networks.
  • Passive Device Option: Can work without external power (in passive hubs).

 Disadvantages of a Hub:

  • No Data Filtering – Sends data to all devices, not just the target one.
  • Network Collisions – High risk of data collisions, especially with many devices.
  • Low Security – All data is visible to all connected devices, making it insecure.
  • Slower Speeds – Shares bandwidth between all devices, reducing overall performance.
  • Obsolete Technology – Outdated and largely replaced by smarter devices like switches.