This section describes the WAN design methodology and the application and technical requirement aspects of WAN design “Applying a Methodology to Network Design.” The network designer should follow these steps when planning and designing the Enterprise Edge based on the PPDIOO methodology:

Step 1 Analyzing customer requirements: The initial step in the design methodology is to analyze the requirements of the network and its users, including the type of applications, the traffic volume, and traffic patterns. User needs continually change in response to changing business conditions and changing technology. For example, as more voice and video-based network applications become available, there is pressure to increase network bandwidth.

Step 2 Characterizing the existing network and sites: The second step is to analyze the existing networking infrastructure and sites, including the technology used and the location of hosts, servers, terminals, and other end nodes. Together with the network’s physical description, the analysis should evaluate the possibility of extending the network to support new sites, new features, or the reallocation of existing nodes. For example, the future integration of data and telephone systems requires considerable changes in the network’s configuration. In this case, a detailed evaluation of current options is important.

Step 3 Designing the network topology and solutions: The final step in the design methodology is to develop the overall network topology and its appropriate services, based on the availability of technology, and taking into account the projected traffic pattern, technology performance constraints, and network reliability. The design document describes a set of discrete functions performed by the Enterprise Edge modules and the expected level of service provided by each selected technology, as dictated by the SP.