Exam Essentials

Remember the benefits of hierarchical network topology design. Hierarchical networks are easier to scale, they permit easier manageability, they offer better performance, and they minimize support and troubleshooting costs.

Understand the layers and design use of the Cisco three-layer hierarchical model. The core layer is responsible for high-speed, low-latency traffic flow and should not include traffic-management design controls. The distribution layer is where traffic control occurs in the hierarchical model and should include traffic-management designs. The access layer at the bottom of the model controls user and workgroup access to the internetwork and can include access control and network policies much like the distribution layer.

Remember the three functional areas of the Enterprise Composite Network Model. The three functional areas of the Enterprise Composite Network Model are Enterprise Campus, Enterprise Edge, and Service Provider Edge. Each functional area is made up of several modules.

Remember the fault-tolerant topology design redundancies. HSRP allows devices to keep working through their default router, even when that router fails, by using a phantom router to switch between redundant routers. Proxy ARP–configured routers provide redundancy to workstations since the workstation doesn’t need a hard-coded default gateway and routers can be replaced and located again. DDR allows a redundant link to provide backup in case the primary link fails or is under heavy load.