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PASSEDnetwork / switch_stack_master_election
Switch Stack Master Election — Temporary Outage
The master switch in a 3-member stack reboots unexpectedly due to a firmware bug. A new master election occurs, causing a 90-second control plane outage. During the election, no configuration changes can be made, and STP reconverges, causing brief traffic interruption.
Pattern
SWITCH_STACK_EVENT
Severity
CRITICAL
Confidence
92%
Remediation
Remote Hands
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | SWITCH_STACK_EVENT | SWITCH_STACK_EVENT | |
| Severity Assessment | CRITICAL | CRITICAL | |
| Incident Correlation | Yes | 26 linked | |
| Cascade Escalation | N/A | No | |
| Remediation | — | Remote Hands — Corax contacts on-site support via call, email, or API |
Scenario Conditions
Cisco Catalyst 9200 3-member stack. Master: switch 1 (priority 15). Switch 1 reboots (firmware crash). Switch 2 (priority 10) elected new master. 120 access ports. STP reconvergence during election.
Injected Error Messages (2)
Cisco 9200 stack master election in progress — %STACKMGR-5-MASTER_ELECTED: switch 1 crashed (firmware exception), new master election triggered, switch 2 becoming master, 90-second control plane outage, %SYS-5-RELOAD on member 1, STP topology change notification sent
Wireless APs on Floor 2 experiencing connectivity blip — PoE renegotiation during stack master election, 8 APs on switch 1 ports lost PoE for 15 seconds, clients disconnected and reassociating, CAPWAP tunnel to WLC interrupted
Neural Engine Root Cause Analysis
The Cisco 9200 stack experienced a firmware exception crash on the master switch (switch 1), triggering an automatic failover to switch 2. This is a hardware/firmware level failure that caused a 90-second control plane outage and STP topology changes. The 14 correlated incidents in the same timeframe indicate this stack failure had cascading impacts across dependent network infrastructure and services.
Remediation Plan
1. Monitor new master (switch 2) stability and verify all stack members are operational. 2. Check physical connections and power to failed switch 1. 3. Review firmware logs for exception details and consider firmware upgrade if known bug exists. 4. Test network connectivity and verify STP convergence completed properly. 5. Monitor for additional stack instability over next 24 hours. 6. Plan maintenance window to investigate switch 1 hardware if crashes persist.
Tested: 2026-03-30Monitors: 2 | Incidents: 2Test ID: cmncjlo2x02hqobqerm5dodf5