Ethernet Video Series


Episode 04, Segment 01 of 03

Ethernet Hubs

An Ethernet hub merges several Ethernet connectors onto a single Ethernet segment. This is an Ethernet hub:

Itís a very dumb device that merges one, or two, or three, or four Ethernet connectors onto a single Ethernet segment. Its intelligence comes at a very low level. It understands only Ethernet. It doesnít know what IP is, and it doesnít care. So we can say that it works beneath IPís radar. Think of an Ethernet hub the same way you think of an old extension cord and multiple outlet strip.

You plug it in in one place where youíve got one connector, and it gives you shared access to several new connectors. Typically, these devices will have light-emitting diodes: lights, indicating how they work for diagnostic purposes. In this case, the lights are directly above the connectors, so I like to mount this one with the connectors facing outward so I can see both the wires and the lights.

You use an Ethernet hub wherever you have a low-cost network, and may need to connect two or more computers to a single Ethernet segment. As soon as two or more devices are connected to this hub, they can use Ethernet to connect with each other from then on.

However, don't attribute too much intelligence to this hub. It's a pretty dumb device. It mindlessly adds more Ethernet connectors, without interpreting any of the transmitted information. Itís not smart enough to share an Internet or an IP address. For that, you need a router.

Ethernet hubs come in a variety of sizes and shapes, from many vendors.

Hereís a four-port one where the connectors are on the back, and the LED indicators are on the front panel Ė a very common configuration.

Hereís another four-port hub that has the same arrangement, with the connectors all on the back, and the diagnostic indicators (LEDís) on the front. They all typically have an external power supply.

This little one actually has a fifth connector for a BNC style of Ethernet Ė an old style of Ethernet that is not in common use anymore.

All of these hubs relay, or broadcast, all of the signals from any connector to every connector. Like an old extension cord or outlet strip, any signal thatís present at any connector is present at all of them.

Episode 04, Segment 02 of 03