Editing Hierarchical routing (section)

==Description==
Hierarchical routing is the procedure of arranging [[router (computing)|router]]s in a hierarchical manner. A good example would be to consider a corporate [[intranet]]. Most corporate intranets consist of a high speed [[backbone network]]. Connected to this backbone are routers which are in turn connected to a particular workgroup. These workgroups occupy a unique [[local area network|LAN]]. The reason this is a good arrangement is because even though there might be dozens of different workgroups, the span (maximum [[hop count]] to get from one host to any other host on the network) is 2. Even if the workgroups divided their LAN network into smaller partitions, the span could only increase to 4 in this particular example.

Considering alternative solutions with every router connected to every other router, or if every router was connected to 2 routers, shows the convenience of hierarchical routing. It decreases the complexity of [[network topology]], increases routing efficiency, and causes much less [[Network congestion|congestion]] because of fewer routing advertisements. With hierarchical routing, only core routers connected to the backbone are aware of all routes. Routers that lie within a LAN only know about routes in the LAN. Unrecognized destinations are passed to the default route.