The Hierarchical Design Model

The hierarchical network model is a useful high-level tool for designing a reliable network infrastructure. It provides a modular view of a network, making it easier to design and build a scalable network. The Hierarchical Network Model As you may recall from CCNA Exploration: LAN Switching and Wireless, the hierarchical network model divides a network into three layers: Access layer-Grants user access to network devices. In a network campus, the access layer generally incorporates switched LAN devices with ports that provide connectivity to workstations and servers. In the WAN environment, it may provide teleworkers or remote sites access to the corporate network across WAN technology. Distribution layer-Aggregates the wiring closets, using switches to segment workgroups and isolate network problems in a campus environment. Similarly, the distribution layer aggregates WAN connections at the edge of the campus and provides policy-based connectivity. Core layer (also referred to as the backbone) - A high-speed backbone that is designed to switch packets as fast as possible. Because the core is critical for connectivity, it must provide a high level of availability and adapt to changes very quickly. It also provides scalability and fast convergence.