[Cisco] Cause of starting with empty config after reboot [Catalyst 9000]

Target environment

• Catalyst 9000 series switches

Symptoms

• Even though the startup-config is saved, the device starts up with an empty config after rebooting.
• The following log is displayed after starting the device.

%SYS-6-STARTUP_CONFIG_IGNORED: System startup configuration is ignored based on the configuration register setting.

Conditions

Running the show romvar command shows SWITCH_IGNORE_STARTUP_CFG=1.

Switch# show romvar 
...
SWITCH_IGNORE_STARTUP_CFG=1
...

Cause

If SWITCH_IGNORE_STARTUP_CFG=1 is set in the rommon variable, startup-config will be ignored when starting the device.

How to respond

The rommon variable SWITCH_IGNORE_STARTUP_CFG must be configured as 0.

First configure the boot manual to boot into rommon when the device boots.

Switch#conf t
Switch(config)#boot manual

After configuration, verify that Manual boot = yes with the show boot command.

Switch#show boot
---------------------------
Switch 1
---------------------------
Current Boot Variables:
BOOT variable does not exist

Boot Variables on next reload:
BOOT variable = flash:packages.conf
Manual Boot = yes
Enable Break = no
Boot Mode = DEVICE
iPXE Timeout = 0

Then run reload.

Switch#reload

Verify that you see the switch: prompt after booting. And configure SWITCH_IGNORE_STARTUP_CFG=0. Then run boot flash:packages.conf to boot IOS-XE.

switch: SWITCH_IGNORE_STARTUP_CFG=0
switch: boot flash:packages.conf

After starting IOS-XE, make sure the startup-config is loaded. Then revert the boot manual configuration to no boot manual.

Switch#conf t
Switch(config)#no boot manual

Then run the show boot command and make sure it says Manual Boot = no.

Switch##show boot man    
---------------------------
Switch 1
---------------------------
Current Boot Variables:
BOOT variable does not exist

Boot Variables on next reload:
BOOT variable = flash:packages.conf
Manual Boot = no
Enable Break = no
Boot Mode = DEVICE
iPXE Timeout = 0

That’s all for now.

References

Configuration Register equivalent CLIs in IOS-XE

ThisdocumentdescribeshowtomodifycertainsystemparametersusingCLIcommandsonCatalyst9000switchesrunningCisco®IOS-XE.

www.cisco.com

Cisco Device Configuration Information Summary

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2021.11.01