IMPLEMENTATION AND EVALUATION OF NETWORK-LEVEL ZERO TRUST CONTROLS FOR ENTERPRISE NETWORK SECURITY USING CISCO PACKET TRACER

Abstract

This study aimed to implement and evaluate selected network-level Zero Trust controls within a simulated enterprise environment using Cisco Packet Tracer to mitigate unauthorized internal communication and lateral movement. A before-and-after experimental design was established across five logical Virtual Local Area Network (VLAN) segments—Finance, Human Resources, Information Technology, Guest, and Server—using Extended Access Control Lists (ACLs), controlled inter-VLAN routing, least-privilege access, and default-deny policy enforcement. Experimental connectivity testing across six documented scenarios demonstrated that all three authorized communication paths remained operational after policy implementation, whereas all three restricted scenarios were successfully blocked. The findings demonstrate that VLAN segmentation alone is insufficient for isolation once inter-VLAN routing is enabled, proving that explicit ACL enforcement is required to achieve effective, policy-based network isolation and prevent lateral movement