ABSTRACT
The typical wide area network (WAN) design for most IBM computing environments is spoke-and-hub. Usually, a mainframe is located at a central point through which all data from every remote site must pass. This topology is illustrated in Exhibit 1. If a site in northern California must communicate with a site in southern California, the data is sent from northern California to the mainframe at corporate headquarters on the east coast and then to southern California. Both time and money are wasted, as the sites are bearing the cost of sending the data on the long trip through the hub. If the spoke-and-hub network connects Token Ring LANs , the seven- hop count limit must be considered; it may be exceeded if widely distributed LANs have to communicate with each other through the central point.
