What is a Hub?

Ethernet and Network Hubs Explained

Multicolored cables
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In computer networking, a hub is a small, simple, inexpensive electronic device that joins multiple computers together.

Until the early 2000s, Ethernet hubs were widely used for home networking due to their simplicity and low cost. While broadband routers have replaced them in homes, hubs still serve a useful purpose. Beside Ethernet, a few other types of networks hubs also exist including USB hubs.

Characteristics of Ethernet Hubs

A hub is a rectangular box, often made of plastic, that receives its power from an ordinary wall outlet. A hub joins multiple computers (or other network devices) together to form a single network segment. On this network segment, all computers can communicate directly with each other.

Ethernet hubs vary in the speed (network data rate or bandwidth) they support. Original Ethernet hubs offered only 10 Mbps rated speeds. Newer types of hubs added 100 Mbps support and usually offered both 10 Mbps and 100 Mbps capabilities (so-called dual-speed or 10/100 hubs).

The number of ports an Ethernet hub supports also varies. Four- and five-port Ethernet hubs are most common in home networks, but eight- and 16-port hubs can be found in some home and small office environments. Hubs can be connected to each other to expand the total number of devices a hub network can support.

Older Ethernet hubs were relatively large in size and sometimes noisy as they contained built in fans for cooling the unit. Modern hub devices are much smaller, designed for mobility, and noiseless.

Passive, Active and Intelligent Hubs

Three basic types of hubs exist:

  • passive
  • active
  • intelligent

Passive hubs do not amplify the electrical signal of incoming packets before broadcasting them out to the network.

 Active hubs, on the other hand, do perform this amplification, as does a different type of dedicated network device called a repeater. Some people use the terms concentrator when referring to a passive hub and multiport repeater when referring to an active hub.

Intelligent hubs add extra features to an active hub that are of particular importance to businesses. An intelligent hub typically is stackable (built in such a way that multiple units can be placed one on top of the other to conserve space). Intelligent Ethernet hubs also typically includes remote management capabilities via SNMP and virtual LAN (VLAN) support.

Working With Ethernet Hubs

To network a group of computers using an Ethernet hub, first connect an Ethernet cable into the unit, then connect the other end of the cable to each computer's network interface card (NIC). All Ethernet hubs accept the RJ-45 connectors of standard Ethernet cables.

To expand a network to accommodate more devices, Ethernet hubs can also be connected to each other, to switches, or to routers.

When an Ethernet Hub is Needed

Ethernet hubs operate as Layer 1 devices in the OSI model. Although hubs comparable functionality, nearly all mainstream Ethernet network equipment today utilizes network switch technology instead, due to the performance benefits of switches.

A hub can be useful for temporarily replacing a broken network switch or when performance is not a critical factor on the network.

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