Washington Elementary School District WAN Hierarchy and Traffic Flow Model

The diagram above demonstrates the two-layer hierarchy of the district WAN. The Core layer consists of three routers located at Phoenix N.W., Sunnyslope, and Greenway, connected by relatively slow point-to-point T1 links. The Access layer consists of individual school routers and their attached Administrative and Curriculum networks, which are connected by high-speed category 5 or 6 cable.

A priority in WAN design is to ensure efficient use of expensive WAN links by restricting the amount of traffic that crosses the link. The above diagram also demonstrates how traffic will flow between networks in the same school, between networks at two different schools, and between networks and the Internet. Traffic between networks at the same school stays within the Access layer. Only traffic addressed to destinations outside of the school are permitted on the WAN links.