|  | 3.3 | How to Identify and Select Networking Capabilities
| 3.3.10 | The benefits of hierarchical WAN designs
One of the advantages of a hierarchical WAN design is that it provides a method for controlling data traffic patterns by putting Layer 3 routing points throughout the network. Because routers have the ability to determine paths from the source host to destination hosts based on Layer 3 addressing, data traffic flows up the hierarchy only as far as it needs to find the destination host, as shown in Figure . If Host A were to establish a connection to Host B, the traffic from this connection would travel to Router 1 and be forwarded back down to Host B. Notice in Figure that this connection does not require that any traffic be placed on the link between Router 1 and Router 2, thus conserving the bandwidth on that link. In a two-layer WAN hierarchy, shown in Figure , the traffic only travels up the hierarchy as far as needed to get to the destination, thus conserving bandwidth on other WAN links.