Networking Before Layer 2 Switching
Because knowing the history of something really helps with understanding why things are the way they are today, I’m going to go back in time a bit and talk about the condition of networks before switches and the part switches have played in the evolution of corporate LANs by helping to segment them. For a visual of how a typical network design looked before LAN switching, check out the network in Figure 11.1.
Figure 11.1 A network before switching
The design in Figure 11.1 was called a collapsed backbone because all the hosts involved had to go to the corporate backbone in order to reach any network services—both LAN and mainframe.
Going back even further, before networks like the one shown in Figure 11.1 had physical segmentation devices such as routers and hubs, there was the mainframe network. This type of network comprised mainframe controllers made by IBM, Honeywell, Sperry, DEC, and so on and dumb terminals that connected into...
