Routing Hierarchies Flat routing doesn'tscale Storage> Each node cannot be expected to store routes to every destination (or destination network) Convergence times increase Communication Total message count increases w Key observation Need less information with increasing distance to destination k Need lower diameters networks Solution area hierarchy 2021/1/31 4Routing Hierarchies  Flat routing doesn’t scale  Storage → Each node cannot be expected to store routes to every destination (or destination network)  Convergence times increase  Communication → Total message count increases  Key observation  Need less information with increasing distance to destination  Need lower diameters networks  Solution: area hierarchy 2021/1/31 4