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Cisco Bug: CSCvh86136 - CMCC Crash Due To CMAND Busy Processing I2C Transactions

Last Modified

Nov 27, 2019

Products (1)

  • Cisco Catalyst 9400 Series Switches

Known Affected Releases

16.6.2

Description (partial)

Symptom:
Catalyst 9400 running IOS-XE versions of code earlier than 16.9.3 are vulnerable to this defect which can cause an unexpected reboot/crash.

The issue has only been seen when there is adjustment of the PSUs/input power to the PSUs. 

If you suspect your Catalyst 9400 has experienced this defect check the output of "show version" to see what the last reload reason is. 

Output from "show logging" may also demonstrate the following:

Mar 12 13:14:48.370 PDT: %CMCC-3-HB_TIMEOUT:  R0/0: cmcc:  Peroidic Heartbeat message from RP timed out.
Mar 12 13:14:48.371 PDT: %IOSXE-4-PLATFORM:  R0/0: kernel: Process : cmcc (27429) encountered fatal signal 6
Mar 12 13:14:48.439 PDT: %IOSXE-3-PLATFORM:  R0/0: Mar 12 13:14:48 pman.sh: %PMAN-3-RELOAD_RP: Reloading: RP will be reloaded
Mar 12 13:14:48.610 PDT: %IOSXE-3-PLATFORM:  R0/0: Mar 12 13:14:48 pman.sh: %PMAN-3-RPSWITCH: RP switch initiated. Critical process cmcc has failed (rc 0)
Mar 12 13:14:48.659 PDT: %IOSXE-3-PLATFORM:  R0/0: Mar 12 13:14:48 pman.sh: %PMAN-3-PROCHOLDDOWN: The process cmcc has been helddown (rc 134)
Mar 12 13:14:48.697 PDT: %IOSXE-0-PLATFORM:  R0/0: Mar 12 13:14:48 pvp.sh: %PMAN-0-PROCFAILCRIT: A critical process cmcc has failed (rc 134)
Mar 12 13:14:48.720 PDT: %IOSXE-3-PLATFORM:  R0/0: Mar 12 13:14:48 pman.sh: %PMAN-3-PROCHOLDDOWN: The process cmcc has been helddown (rc 134)
Mar 12 13:14:48.758 PDT: %IOSXE-0-PLATFORM:  R0/0: Mar 12 13:14:48 pvp.sh: %PMAN-0-PROCFAILCRIT: A critical process cmcc has failed (rc 134)

Additionally, the last reload reason of the 9400 may show this: Critical process cmand fault on rp_1_0 (rc=134)

If these are seen, engage Cisco TAC for additional troubleshooting assistance.

Conditions:
Catalyst 9400 running IOS-XE versions of code earlier than 16.9.3 in conjunction with adjustment of the PSUs/input power to the PSUs can potentially run into the defect.
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