Cisco Certified Network Professional (CCNP) Question:
How does the use of a hierarchical routing structure (access, distribution, and core) enable a scalable delivery system?
Answer:
If a delivery system is not divided into access, distribution, and core layers, every point in the system needs to maintain every possible destination address to make a delivery decision. The use of a layered system means each layer needs only the information necessary to deliver to the next layer, either above or below.