Figure 1 shows a 5 story building. Each floor has its on switch attached to a router interface. Each floor is a separate network. Figure 2 shows a router connected to the Internet and to four LANs. Each LAN is assigned an organization unit: administration, human resource, students, accounting. Figure 3 shows a router connected to the Internet and to three LANs. Each LAN is assigned to a device type: all hosts, all servers, all printers.