Symptoms: Network Experiencing Broadcast Storm and High CPU on Switches

• Multiple switches in the access layer are showing 90-100% CPU utilization.
• Network connectivity is severely degraded; ping between hosts shows massive packet loss and multi-second latency.
• Switch logs show MAC address flapping warnings: the same MAC is seen on multiple ports rapidly.
• Broadcast traffic has saturated trunk links; SNMP monitoring shows interface utilization at 100%.
• The issue started approximately 15 minutes ago without any planned changes.
• Spanning Tree logs show topology change notifications (TCN) flooding at high rates.
• Some switches have become unresponsive to management (SSH/SNMP timeouts).
• End users report complete loss of network connectivity across the affected building.
• The problem is isolated to VLANs 10 and 20, which share the same switch infrastructure.