In a bus backbone, the topology of the backbone is a bus.
Bus backbone are normally used as a distribution backbone to connect different buildings in an organization. Each building can comprise either a single LAN or another backbone ( normally a star backbone). A good example of a bus backbone is one that connects single- or multiple-floor buildings on a campus. Each single - floor building usually has a single LAN. Each multiple - floor building has a backbone ( usually a star) that connects each LAN on a floor. A bus backbone can interconnect these LANs and backbones. Figure 15.12 shows an example of a bridge - based backbone with four LANs.