Design and Implementation of a Redundant Three-Tier Campus Network with Dual ISP Connectivity

Abstract

Modern campus networks often face issues such as single points of failure, limited scalability, and inefficient traffic handling, especially when relying on a single ISP or non-hierarchical design. These limitations can lead to service disruption and reduced network performance in real-world environments. This project presents the design and implementation of a redundant three-tier campus smart network with dual ISP connectivity using Cisco Packet Tracer. The architecture follows core, distribution, and access layers, where redundancy is ensured at each level through dual core routers and multilayer switches. Dual ISP connections are configured using OSPF with cost-based path selection to enable automatic failover between primary and secondary links The implementation includes VLAN configuration on access switches to segment student and staff networks, along with inter-VLAN routing using multilayer switches and HSRP for gateway redundancy. Dynamic routing with OSPF ensures efficient communication [9], while centralized wireless access is managed using a WLC and APs. Additionally, services like DHCP, DNS, and email servers are integrated, and ACLs are applied to control inter-VLAN access. During the simulation, challenges such as OSPF neighbor formation, VLAN trunking, and failover stability were encountered and resolved through testing. Failover was verified by shutting down the primary ISP link, where traffic successfully rerouted through the backup link without interruption. The results show that the proposed design provides high availability, better traffic management [9], and improved security, making it suitable for real-world campus network deployment.