A hub is a basic network device that operates at the physical layer (Layer 1) of the OSI model. Its primary function is to connect multiple devices in a local area network (LAN) and transmit data from one device to all other devices connected to it. Hubs have largely been phased out in modern networking in favor of more intelligent devices like switches, which operate at higher layers of the OSI model and offer better performance and efficiency. Here are some key points about hubs:
- Broadcasting: Hubs operate by broadcasting data to all devices connected to them. When one device sends data to the hub, the hub rebroadcasts that data to all other devices. This can lead to network congestion and inefficiency.
- Collision Domain: In a hub-based network, all connected devices share the same collision domain. This means that if two devices attempt to transmit data simultaneously, a collision occurs, and the data may need to be retransmitted.
- Unintelligent: Hubs are considered “dumb” devices because they do not make any decisions about where to send data. They lack the ability to store and forward data to specific devices, as switches do.
- Limited to Ethernet: Hubs are typically used in Ethernet networks and are available in various types, such as 10/100 Mbps hubs and older 10 Mbps hubs.
- Obsolete in Modern Networks: Due to their limitations and inefficiencies, hubs have become obsolete in modern networks. They have been largely replaced by network switches, which are more intelligent and efficient at managing network traffic.
- Simple and Inexpensive: One advantage of hubs is their simplicity and low cost. However, this simplicity comes at the expense of network performance.
- Use Cases: In some cases, hubs may still be used for network monitoring or troubleshooting purposes, where network traffic needs to be captured or monitored without causing disruption to the network. However, these use cases are limited.
It’s important to note that the use of traditional hubs in networking has largely been replaced by network switches. Network switches are more efficient and capable of making intelligent forwarding decisions based on MAC addresses, reducing network congestion and collisions. If you’re setting up a modern network, a network switch is typically the preferred choice over using hubs.
Here are the main types of hubs that were commonly used:
- Active Hub (Repeater Hub): Active hubs, also known as repeater hubs, were equipped with signal amplification and regeneration capabilities. They could extend the distance that network signals could travel, making them useful for large network installations. These hubs would receive incoming signals, amplify them, and then retransmit them to all other ports. Active hubs were more reliable than passive hubs because they could boost weak signals.
- Passive Hub (Non-Powered Hub): Passive hubs, also known as non-powered hubs, were simple devices that lacked signal amplification or regeneration. They merely passed data from one port to all other ports without boosting the signal. Passive hubs were limited in the distance they could support and were typically used for small networks with devices in close proximity.
- Intelligent Hub: An intelligent hub was a hub with more advanced features than a typical passive or active hub. It could monitor network traffic, detect errors, and sometimes even provide simple management capabilities. These hubs were more suitable for larger networks where basic monitoring and management were necessary.
- Switching Hub (Smart Hub): Although the term “switching hub” might sound like a contradiction, some hubs were designed to offer limited switching functionality. They were more advanced than traditional hubs but not as capable as full-fledged network switches. These devices could make forwarding decisions based on MAC addresses, reducing the likelihood of network collisions and improving efficiency compared to standard hubs.
- USB Hub: While not a network hub, a USB hub serves a similar purpose in the context of USB connections. It allows multiple USB devices to be connected to a single USB port on a computer. USB hubs are commonly used for expanding the number of USB peripherals that can be attached to a computer.
In summary, while hubs were once commonly used to connect devices in Ethernet networks, they are no longer practical for most modern networking needs. Network switches have largely replaced hubs because they can intelligently direct data to specific devices, reduce network collisions, and provide better network performance and efficiency.
