Perhaps the most popular hybrid topology is the hierarchical configuration. It
consists of several levels of distributed computer systems. Computer systems at
each level download part of their processing tasks to lower levels and upload sum-
mary data to higher levels. This topology is well suited to a manufacturing firm hav-
ing a home office and remote plants, warehouses, and sales offices. Figure 3-4
pictures a simple companywide distributed hierarchical WAN topology for such a
firm. The lighting bolts—depicting telecommunications links (e.g., dial-up telephone
service, wide-area telephone service, or leased lines)—denote, for example, that the
manufacturing plant and marketing office are geographically distant from the home
office. Note also that the manufacturing plant is connected to two LANs, one in the
production planning department and one in the engineering department.