As the name implies, repeaters are simple devices that boost a signal’s ability to travel farther and faster on the network (because it is repeating the signal). You will need to buy a repeater when the total length of a segment of your network cabling is larger than the maximum for your cable type. For instance, 10Base2 coaxial has a maximum length of 185 meters, and 10/10BaseT twisted pair has a maximum length of 100 meters. Somewhere before the 185 and 100 meters mark is finished, you will need to provide a repeater to extend the signal.
A general rule of them for the Ethernet networks is that three repeaters is the maximum number of devices that a signal can pass through before it will go bad. Simple logic might indicate that you could attach an unlimited number of repeaters if, in fact, that’s what the repeaters do for the signal: repeat it. Unfortunately, that’s not the case at all. You can have more repeaters than three but you’ll have to plan your network so that the signal is able to pass through with only three repeaters.
If you have two hubs that are daisychained together so that all 14 devices on both hubs are able to communicate with each other, you can attach a repeater to extend the length of the weakening signal.
Two-port 10Base2 (using coaxial cable) repeaters are expensive and are rarely used because of the expense of the equipment.
One other note about repeaters is that the 185 meter and 100 meter maximum cable length refers to your ability to tie the two segments together; they don’t actually extend the length of a single segment. That’s handy to know when you have two disparate lengths combined for those totals.
As you will see when you study this subject in more detail, some of the 10/100BaseT hubs have a Bayonet Neill-Concelman (commonly called BNC) connector on the backside. In reality, this connector lets you connect a 185 meter segment (thinnet) because the BNC connector itself is a thinnet repeater. The segment can attach 10BaseT hubs, separate PCs or both.
So the repeater is a handy device that will enable you to extend the length of your network.
The study of networking equipment and techniques is fascinating because of the variety of possible interconnections each piece of equipment can have. It’s not enough to know what each device does; its is important to know how they all work together harmoniously.