Root Cause Analysis for Cisco ISE Deployment Issues

This case study details a structured, multi-phase remediation program implemented to address persistent instability in a Cisco Identity Service Engine (ISE) deployment at a large Canadian regional hospital network. The program aimed to stabilize authentication services and eliminate the root causes of latency and outages that had been affecting clinical operations across 17 hospitals and clinics. The methodology involved three phases: immediate stabilization, infrastructure optimization, and policy and architecture modernization. Key actions included optimizing RADIUS policies, tuning backend services, and rationalizing policy sets. The investigation revealed deep configuration, policy, and architectural problems that had gone unresolved for over a year. Results showed a significant reduction in RADIUS latency and SEV1 outages, restoring reliable access across all hospitals. The engagement emphasizes the importance of thorough policy design and operational configuration in maintaining network health, demonstrating that standard health checks may not capture underlying issues.