hubverkko

Hubverkko, commonly referred to as a hub network in English, describes a local area network topology where multiple devices connect to a central device called a hub. The hub acts as a multiport repeater: when it receives a signal on one port, it broadcasts that signal to all other ports, regardless of the destination. All devices connected to a hub therefore share a single collision domain.

Operation and characteristics: A hub is a layer 1 device that does not inspect or store MAC addresses, nor does it route or filter frames. Because every port is part of one shared collision domain, simultaneous transmissions can cause collisions, which are managed by the network’s CSMA/CD protocol in legacy Ethernet environments. Hubs are simple and inexpensive to implement but offer limited bandwidth and no per-port traffic isolation.

Variants and performance: Active hubs include amplifiers to extend signal reach, while passive hubs simply pass signals through with minimal amplification. Compared with switches, hubs provide poor scalability: bandwidth is shared among all ports, collisions increase as more devices are added, and security is weak since all traffic is broadcast to every connected device.

History and current use: Hub networks were common in early Ethernet deployments (10 Mbps) using coaxial cable or early twisted-pair cabling. With the rise of network switches, hubs were largely phased out for new installations because switches can segment collision domains per port, enabling better performance and security. Today, hubs may still be found in simple or educational setups, temporary labs, or legacy systems.

See also: Ethernet, switch, star topology, collision domain.