Networking - Network Component - Hub
A hub is a basic networking device that connects multiple devices in a network. It operates at the Physical Layer (Layer 1) of the OSI (Open Systems Interconnection) model. Unlike switches, which operate at the Data Link Layer (Layer 2), hubs are not capable of making intelligent forwarding decisions based on MAC addresses. Instead, they simply broadcast incoming data packets to all connected devices.
Here are some key points about hubs:
- Function: A hub receives incoming data packets from one device and broadcasts them to all other connected devices on the network. This process is known as data packet replication or data packet broadcasting. Every device connected to the hub receives all transmitted data, regardless of the destination device.
- Broadcast Domain: Since a hub broadcasts data to all connected devices, it creates a single broadcast domain. This means that when one device sends a broadcast message, all devices connected to the hub will receive it. Broadcast traffic can consume network bandwidth and may cause congestion on the network.
- Collision Domain: In a hub-based network, all connected devices share the same collision domain. When multiple devices transmit data simultaneously, a collision can occur, resulting in data loss or corruption. Hubs do not perform collision detection or mitigation. As a result, network performance and efficiency are lower compared to switches, which have collision avoidance mechanisms.
Types of Hubs:
- Passive Hub: A passive hub simply broadcasts incoming data packets to all connected devices without amplifying or regenerating the signals. It is a simple, low-cost device with no built-in intelligence.
- Active Hub: An active hub, also known as a powered hub, includes built-in signal amplification and regeneration capabilities. It strengthens the incoming signals before broadcasting them to connected devices. Active hubs are typically used to extend the network's physical reach and overcome limitations related to signal attenuation.
Advantages of Hubs:
- Simplicity: Hubs are straightforward devices with minimal configuration requirements. They are easy to install and maintain.
- Cost: Hubs are generally less expensive than switches, making them an affordable option for basic networking needs.
- Network Expansion: Hubs can be used to expand the number of available ports in a network by providing additional connection points for devices.
Disadvantages of Hubs:
- Network Performance: Since hubs broadcast data to all connected devices, network performance can be negatively affected, especially in larger networks with significant data traffic.
- Collision and Broadcast Domains: Hubs create a single collision and broadcast domain, limiting network efficiency and scalability.
- Lack of Intelligent Forwarding: Hubs do not have the ability to make intelligent forwarding decisions based on MAC addresses. This can result in unnecessary network traffic and reduced network efficiency.