terminators to be installed at the end of cable runs. When these couplers or terminators were removed, the entire network would stop working. These cables formed the physical backbones for Ethernet networks. With the introduction of Ethernet running over unshielded twisted pair (UTP) cables terminated with RJ45 connectors, hubs became the new backbones in most installa- tions. Many companies attached hubs to their existing thin-net networks to allow greater flexibility as well. Hubs were made to support UTP and BNC 10Base-2 installa- tions, but UTP was SO much easier to work with that it became the de facto standard. A hub is simply a means of connecting Ethernet cables together SO that their signals can be repeated to every other connected cable on the hub. Hubs may also be called repeaters for this reason, but it is important to understand that while a hub is a repeater, a repeater is not necessarily a hub. A repeater repeats a signal. Repeaters are usually used to extend a connection to a remote host, or to connect a group of users who exceed the distance limitation of 10Base-T. In other words, if the usable distance of a 10Base-T cable is exceeded, a repeater can be placed inline to increase the usable distance. I was surprised to learn that there is no specific distance limitation included in the 10Base-T standard. While 10Base-5 and 10Base-2 do include distance limitations (500 meters and 200 meters, respec- tively), the 10Base-T spec instead describes certain characteristics that a cable should meet. To be safe, I usually try to keep my 10Base-T cables within 100 meters. Segments are divided by repeaters or hubs. Figure 2-1 shows a repeater extending the distance between a server and a personal computer. Repeater Figure 2-1. Repeater extending a single 10Base-T link A hub is like a repeater, except that while a repeater may have only two connectors, a hub can have many more; that is, it repeats a signal over many cables as opposed to just one. Figure 2-2 shows a hub connecting several computers to a networ