When an enterprise core switch or edge router reloads unexpectedly or experiences a control-plane stall, operational teams face acute pressure to restore service while preserving forensic evidence. In high-severity outages, standard rebooting without collecting diagnostic state destroys volatile data required to identify the root cause. This guide outlines standard Cisco TAC escalation procedures for managing catastrophic failures on Cisco IOS-XE and NX-OS platforms: core dump extraction, crashinfo analysis, triage packaging, and bug scrubbing.
Immediate Incident Triage: Preserving Volatile State
Before executing a power cycle or manual reboot on a malfunctioning chassis, determine whether the control plane or the data plane is impaired. If packets are forwarding through ASICs but SSH/console sessions respond sluggishly, the issue is confined to the Route Processor (RP) CPU or memory.
Collect fundamental state metrics before resetting the system:
Router# show version | include uptime|reloaded
Router uptime is 14 weeks, 2 days, 4 hours, 12 minutes
System returned to ROM by reload at 04:12:09 UTC Sat Oct 24 2026
System image file is "bootflash:packages.conf"
Router# show logging | include %SYS-2-SYSTEM_RELOAD|%SOFTWARE-|EXCEPTION
Oct 24 04:11:45.102 UTC: %SYS-2-SYSTEM_RELOAD: Critical process fed faulted, initiating reload
Oct 24 04:11:45.105 UTC: %IOSXE-3-PLATFORM: Process fed had critical failure (SIGSEGV)
If terminal access is available during high CPU events, identify the specific task starving the control plane:
Router# show processes cpu sorted | exclude 0.0%
CPU utilization for five seconds: 99%/12%; one minute: 98%; five minutes: 95%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
142 14295192 1049212 13624 84.2% 82.1% 79.4% 0 IOS-XE RP Punt
89 1941295 4910214 395 4.5% 4.2% 4.1% 0 BGP Router
An elevated IOS-XE RP Punt process signifies that hardware forwarding ASICs are punt-injecting packets to the CPU, indicating an ARP storm, broadcast loop, or unhandled transit traffic hitting CPU punt paths.
Core Dump and Crashinfo Extraction
Modern Cisco platforms running Cisco IOS-XE (such as Catalyst 9000, ASR 1000, and Catalyst 8000) partition operating system memory into kernel space and user space daemon processes. When an individual daemon fails, the system generates a crashinfo text log and a binary core dump file.
Locating Crash Files on Storage
Router# dir bootflash:crashinfo*
Directory of bootflash:/crashinfo*
142104 -rw- 419512 Oct 24 2026 04:12:15 +00:00 crashinfo_RP_00_00_20261024-041215-UTC
142105 -rw- 84192041 Oct 24 2026 04:12:18 +00:00 core.fed.14215.20261024-041215.gz
Decoding Crashinfo Headers
The text file crashinfo_RP_* provides immediate failure attribution without requiring specialized debuggers:
------------------ Exception Record ------------------
Fatal signal: 11 (SIGSEGV) at PC 0x7f9214b219a0
Fault address: 0x0000000000000028
Process: fed (Forwarding Engine Driver)
Thread: fed_main_thread
Registers:
RA: 0x00007f9214b218f0 SP: 0x00007ffe8192a010
PC: 0x00007f9214b219a0 Flags: 0x0000000000010206
Stack trace:
[0] 0x7f9214b219a0 fed_l3_route_update + 0x140
[1] 0x7f9214a19012 fed_fib_event_handler + 0x82
[2] 0x7f9212004510 thread_dispatch + 0x190
Signal 11 (SIGSEGV) at offset 0x28 indicates a null-pointer dereference inside the Forwarding Engine Driver during an L3 route update. This deterministic signature enables TAC and engineering teams to locate matching software caveats immediately.
Generating Comprehensive System Trace Archives
On Cisco IOS-XE, collect full diagnostic bundles directly using platform commands:
Router# request platform software trace archive target bootflash:tac_archive_case12345.tar.gz
Creating archive file [bootflash:tac_archive_case12345.tar.gz]
Archiving trace logs from RP0...
Archiving trace logs from ESP0...
Archive file created successfully.
Packaging Show Tech-Support for TAC Analysis
When submitting diagnostic data to TAC, truncated terminal output creates delays. Always redirect command outputs directly to disk with pagination disabled.
# Disable terminal pagination and line wrap
Router# terminal length 0
Router# terminal width 512
# Redirect base tech-support to bootflash
Router# show tech-support | redirect bootflash:show_tech_base.txt
# Capture platform-specific switching and forwarding state
Router# show tech-support platform | redirect bootflash:show_tech_platform.txt
Verify file sizes on bootflash before uploading to the TAC Case File Uploader:
Router# dir bootflash:show_tech*
Directory of bootflash:/show_tech*
142108 -rw- 12491512 Oct 24 2026 04:45:10 +00:00 show_tech_base.txt
142109 -rw- 24912041 Oct 24 2026 04:47:22 +00:00 show_tech_platform.txt
Proactive Bug Scrub Methodology
Resolving a crash permanently requires identifying whether the failure matches a known defect or represents a novel bug. Follow this structured bug scrub sequence:
1. Extract the Defect Signature
From the crashinfo or system logs, extract three data points:
- Software release:
17.09.04a - Affected process or module:
fed(Forwarding Engine Driver) - Triggering function / stack frame:
fed_l3_route_update
2. Query the Cisco Bug Search Tool (BST)
Search with syntax: IOS-XE 17.9 fed crash fed_l3_route_update.
Evaluate matching bugs for:
- State: Fixed
- Known Affected Releases:
17.9.4,17.9.4a - First Fixed In:
17.9.5,17.12.2
3. Identify Workarounds and Maintenance Upgrades
If an immediate software upgrade cannot be scheduled during operational hours, evaluate documented workarounds (such as disabling specific routing recursion features or applying an in-service Software Maintenance Upgrade / SMU patch).
# Verify installed SMU patches on Cisco IOS-XE
Router# show install active | include SMU|fix
Post-Incident Deliverable Checklist
- Binary core dump file (
core.*.gz) and text crashinfo file copied off-box to secure archival storage. - Complete
show tech-supportandshow tech-support platformgenerated with pagination disabled. - System trace archive (
.tar.gz) collected within two hours of incident recovery. - Cisco TAC case opened with precise defect signature, hardware serial numbers, and exact timeline of topology events preceding the reload.