A network hub is a node that broadcasts data to every computer or Ethernet-based device connected to it. A hub is less sophisticated than a switch, the latter of which can isolate data transmissions to specific devices.
Network hubs are best suited for small, simple local area network (LAN) environments. Hubs cannot provide routing capabilities or other advanced network services. Because they operate by forwarding packets across all ports indiscriminately, network hubs are sometimes referred to as "dumb switches."
With limited capabilities and poor scalability, network hubs had primarily one competitive advantage over switches: lower prices. As switch prices fell in the early to mid-2000s, hubs began getting phased out of use. Today, hubs are far less commonly deployed. But network hubs have some niche uses and continue to offer a simple means of networking.
How network hubs work
Network hubs are categorized as Layer 1 devices in the Open Systems Interconnection (OSI) reference model. They connect multiple computers together, transmitting data received at one port to all of its other ports without restriction. Hubs operate in half-duplex.
This model raises security and privacy concerns, because traffic could not be safeguarded or quarantined. It also presents a practical issue in terms of traffic management. Devices on a hub function as a network segment and share a collision domain. Thus, when two devices connected to a network hub transmit data simultaneously, the packets will collide, causing network performance problems. This is mitigated in switches or routers, as each port represents a separate collision domain.
All devices connected to a network hub share all available bandwidth equally. This differs from a switch environment, where each port is allotted a dedicated amount of bandwidth.
Types of hubs
There are two types of network hubs: active and passive. A third designation, intelligent hubs, is synonymous with a switch.
- Active hubs repeat and strengthen incoming transmissions. They are also sometimes referred to as repeaters.
- Passive hubs simply serve as a point of connectivity, without any additional capabilities.
An unrelated use of the word "hub" involves network topologies. In a star topology, sometimes called hub and spoke, each host connects to a central hub; the hosts, however, do not directly connect to each other. In this context, the "hub" is typically a switch.