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PASSEDnetwork / switch_stack_ring_failure
Switch Stack Ring Failure — Stack Split
A Cisco 9300 4-member switch stack experiences a stack cable failure, splitting the stack into two independent 2-member stacks. Both halves claim the same management IP. MAC address tables conflict. Half the access ports become unreachable from management.
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 | 36 linked | |
| Cascade Escalation | Yes | Yes | |
| Remediation | — | Remote Hands — Corax contacts on-site support via call, email, or API |
Scenario Conditions
Cisco Catalyst 9300 4-member stack. StackWise-480 cables in ring topology. Cable between switch 2 and switch 3 failed. Stack splits into [1,2] and [3,4]. Both halves run stack master election. Duplicate management IPs.
Injected Error Messages (3)
Cisco 9300 stack ring failure — %STACKMGR-4-STACK_LINK_CHANGE: stack cable between switch 2 and switch 3 DOWN, stack split detected, ring topology broken, two independent stacks formed [1,2] and [3,4], duplicate management IP 10.0.0.10, %STACKMGR-1-STACK_SPLIT
User subnet intermittent connectivity — switch stack split causing MAC table conflicts, ARP responses from two gateways with different MAC addresses, users on switches 3-4 losing DHCP and DNS, packet duplication on VLAN 20
VoIP phones on switches 3-4 losing registration — stack split isolated VoIP VLAN, SIP REGISTER failing for 40 phones on stack members 3 and 4, audio quality issues on calls traversing split boundary, one-way audio reported
Neural Engine Root Cause Analysis
The Cisco 9300 switch stack has experienced a physical stack cable failure between switch 2 and switch 3, causing the ring topology to break and split into two independent stacks ([1,2] and [3,4]). This has created duplicate management IP addresses (10.0.0.10) on both stack segments, resulting in network conflicts and management plane failures. The 14 correlated incidents within the same time window indicate a significant network disruption affecting multiple dependent services.
Remediation Plan
1. Immediately verify physical stack cable connections between switch 2 and 3 - check for loose, damaged, or failed stack cables. 2. If cable is damaged, replace the stack cable with a known good cable. 3. If cable appears intact, reseat both ends of the stack cable firmly. 4. Power cycle the affected switches in sequence (switch 3 first, then switch 2) to re-establish stack membership. 5. Verify stack ring topology is restored and only one management IP is active. 6. Monitor for stack master election completion and verify all switches rejoin the stack properly. 7. Test connectivity to all stack members and dependent network services.
Tested: 2026-03-30Monitors: 3 | Incidents: 3Test ID: cmncjlncw02hpobqeqvilvgrj