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Supervisor Engine module does not come online due to continuous booting loop, invalid boot variable, incorrect configuration register setting or corrupt image


Core issue

This issue causes the Supervisor Engine to go to ROM Monitor (ROMmon) mode.


To resolve this issue, perform these steps:

  1. Console into the Supervisor engine.    

    If the prompt is displayed as ROMmon, the Supervisor Engine is not able to boot using the Catalyst OS (CatOS) image due to one or more of these reasons:

    • The boot variable is not set correctly.        
    • The configuration register is set to 0x0.        
    • The image on the bootflash is corrupted or deleted.        
  2. Ensure that a valid image is in the bootflash:, or slot0:, by issuing the dir device command from the ROMmon prompt, as shown:

    Rommon 1> dir bootflash:
    !--- Issue this command if the image is in bootflash.
    Rommon 1> dir slot0:
    !--- Issue this command if the image is on a PCMCIA card.   

    If the image listed is correct, try to boot from that image, as shown:

    Rommon 1> boot bootflash:filename 

If the Supervisor Engine boots up properly using the CatOS image, perform these steps:

  1. Verify that the boot variable is pointing to the correct image and that the configuration register is set to 0x2102, by issuing the following command:    
    Console> (enable) show boot

    If it is not set correctly, set the variables by issuing these commands:

    Console> (enable) set boot system flash bootflash:filename 
    Console> (enable) set boot config-register 0x10F
  2. Reset the Supervisor Engine to ensure that it boots up properly. 

For information on software recovery on CatOS-based switches, refer to Recovering Catalyst Switches Running CatOS from Booting Failures.

For information on software recovery on Cisco IOS  Software-based switches, refer to these documents: