A scalable enterprise switching architecture, or enterprise switching architecture, consists of three functional layers: 1. Access Layer - Endpoint connectivity and PoE power engineering (IEEE 802. Aggregation Layer - Inter-VLAN routing, policy enforcement, bandwidth. Cisco 3-Tier Hierarchical Network Topology: BY: Ahmed Malik (Advisor to Cisco ASC/ITC & Director Tech Awareness) The Cisco 3-tier hierarchical network topology is a widely adopted design model for large campus and enterprise networks. It divides the network into three distinct layers: Core. A hands-on guide to designing, cabling, and configuring a hierarchical three-tier network — including VLANs, inter-VLAN routing, subnetting, port security, and troubleshooting.