Explanation/Reference:
2. Benefits of a Hierarchical Network
Scalability: The modularity of the design of hierarchical networks allows you to replicate design elements as the network grows including the use of layer 3 support on network swithces. Because each instance of the module is consistent, expansion is easy to plan and implement. Redundancy: Redundancy at the core and distribution layers ensures path availability in case of any hardware failure in any of the devices on these layers. Performance: Link aggregation between levels and high-performance core and distribution level switches allows for near wire speed throughout the network. Properly designed hierarchical networks can achieve near wire speed between all devices. Security: Port security at the access level, and policies at the distribution layer make the network more secure. is important to keep the core layer free from any tasks that may compromise the speed of the link, all security should be handled at the access and distrubution layers. Manageability: Consistency between switches at each level makes management more simple. Each layer of the hierarchical design performs specific functions that are consistent throughout that layer. Therefore, if you need to change the functionality of an access layer switch, you could repeat that change across all access layer switches in the network because they presumably perform the same functions at their layer.
Maintainability: Because hierarchical networks are modular in nature and scale very easily, they are easy to maintain. With other network topology designs, manageability becomes increasingly complicated as the network grows. In the hierarchical model, switch functions are different at each layer. You can save money by using less expensive access layer switches at the lowest layer, and spend more on the distribution and core layer switches to achieve high performance on the network.