ignal were to be allowed to continue uninterrupted, it would keep bouncing back and forth along the cable, preventing other computers from sending signals. There- fore, the signal must be stopped after it has had a chance to reach the proper desti- nation address. A component called a terminator is placed at each end of the cable to absorb free signals and to clear the cable SO that other computers can send data. The bus topology is a passive topology. Computers only listen for data being sent on the network; they are not responsible for moving data from one computer to the next. An advantage of the bus topology is that it uses short cable lengths, and therefore it uses cable economically. Because the transmission media are inex- pensive and easy to work with, the network is easy to extend. A disadvantage of the bus topology is that problems are difficult to isolate. A cable break can affect many users, and the network can become slow when traffic is heavy. Ring Topology In the ring topology, the nodes are connected by point-to-point links that are arranged to form an unbroken loop configuration. At each station the signal is received, regenerated, and transmitted to the next station on the ring, and data is transmitted in one direction around the ring. The ring is an active topology. That is, each computer acts like a repeater to boost the signal and send it on to the next computer. Because the signal passes through each computer, the failure of one computer can affect the entire network-but in practice this rarely occurs because the ring interfaces contain passive electrical shunts that allow the ring to remain intact in case a station goes down or malfunctions. LAN Interconnection and Internetworking An advantage of the ring topology is that it can spread over long distances because each station regenerates the signal. Another advantage is ease of imple- menting distributed control and checking facilities; all computers have equal access, and the performance is even, despite the fact that there are many users.