Architecting a Multihomed Secondary Internet Network for Enhanced Reliability : Design, Implementation, and Performance Evaluation

Sammanfattning

This thesis investigates the design and evaluation of a dual-ISP multihomed network architecture intended to provide service separation, high availability, and automatic failover. The work is based on a customer-approved Low-Level Design (LLD) and was implemented as a proof-of-concept in a Cisco IOS homelab environment. The implementation used VLAN segmentation, internal BGP (iBGP), Policy-Based Routing (PBR), Network Address Translation (NAT), and IP SLA–based failover mechanisms. A series of controlled tests were conducted to validate connectivity, traffic steering, failover behavior, and baseline network performance. The results showed that dedicated and shared services were successfully routed through their intended ISP connections under normal operating conditions. During simulated ISP outages, traffic automatically failed over to the backup ISP with approximately four seconds of convergence time and 0.4% packet loss. The architecture therefore achieved its primary objectives of service separation and automated failover. The study concludes that the proposed multihomed architecture successfully validates the functional requirements of the original design within the constraints of a homelab environment. While production-grade redundancy features were outside the scope of the implementation, the proof-of-concept demonstrates that Cisco IOS technologies can effectively support multihoming, traffic engineering, and ISP redundancy.