Before Layer 2 Switching
Let's go back in time a bit and take a look at the condition of networks before switches and how switches have helped segment the corporate LAN. Before LAN switching, the typical network design looked like the network in Figure 7.1.
The design in Figure 7.1 was called a collapsed backbone because all hosts needed to go to the corporate backbone to reach any network services—both LAN and mainframe.
Going back even further, before networks like the one shown in Figure 7.1 had physical segmentation devices such as routers and hubs, there was the mainframe network. This network included the mainframe (IBM, Honeywell, Sperry, DEC, etc.), controllers, and dumb terminals that connected into the controller. Any remote sites were ...