edVirtus Reference

What Is a Network Hub?

How Does a Hub Connect Multiple Devices on a Local Area Network?

A network hub is a multiport communication device that connects several Ethernet devices into a single local area network. Operating entirely at the physical layer (Layer 1) of the OSI reference model, a hub simply regenerates and repeats incoming electrical signals to every other port without interpreting the data being transmitted.

The basic principle is straightforward. When a device connected to a hub transmits an Ethernet frame, the hub receives the electrical signal, restores its shape and timing, and immediately retransmits the regenerated signal out of every other port. Every connected device therefore receives every transmitted frame, regardless of which device is the intended recipient. Each receiving device examines the destination Media Access Control (MAC) address and discards any frames not addressed to it.

A useful analogy is a person standing in the centre of a room who repeats every message aloud to everyone present. Every person hears every message, even though only one individual may be the intended recipient. A network hub operates in exactly this manner, distributing all incoming traffic to every connected device.

Because all devices connected to a hub share the same communication medium, they also share the available network bandwidth and belong to a single collision domain. If two devices transmit simultaneously, their signals collide and both transmissions are corrupted. Early Ethernet networks used the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol to detect such collisions, wait for a random interval, and retransmit the affected frames. As the number of connected devices increased, collisions became more frequent and network performance declined.

One advantage of hubs was their simplicity, low cost, and ease of installation. They required no configuration and could be used to extend or centralise early Ethernet networks. However, their inability to isolate traffic, combined with shared bandwidth and frequent collisions, made them increasingly unsuitable as network speeds and traffic volumes grew.

It is important to distinguish a hub from a repeater. A hub is essentially a multiport repeater, providing the signal regeneration function of a repeater while connecting multiple devices. More importantly, a hub differs from an Ethernet switch. A switch operates at the data link layer (Layer 2), learns the MAC addresses associated with each port, and forwards frames only to the appropriate destination port. Each switch port forms its own collision domain and normally supports full-duplex communication, eliminating collisions entirely. A router, by contrast, operates at the network layer (Layer 3) and forwards packets between different IP networks.

Today, network hubs have been almost completely replaced by Ethernet switches in modern local area networks. Switches provide dedicated bandwidth to each connected device, eliminate collisions, improve security by limiting unnecessary traffic, and support much higher network performance. As a result, hubs are now encountered primarily in legacy installations and educational demonstrations illustrating the early operation of Ethernet networks.