How Do I Get a Switch to Choose the Correct IOS Between Two IOS Images at Boot Time?

[Musole2013]

Cisco Gurus,

I blundered today. I loaded a working IOS I use on 3750 switches on a 3750x switch. I was trying to test this IOS on the 3750x. To force it to prefer the added IOS to the one the switch shipped with, I specified and saved in the startup config the IOS to use by running the boot system flash command.

Now for the poser. The IOS is clearly incompatible. The switch is respectfully telling me that the IOS it's trying to load does not support the hardware on the switch. 

How do I regain access to the switch? Both images are OK (i.e. not corrupt) but the switch is choosing the image it can't use because I told it to! I forgot to include the "in-built" IOS among the images it should use in case the added IOS fails. 

Will I need to use xModem? Or is there another way that someone on this forum would recommend or has used before?

[Norberto Salgado · Accepted solution]

Hi,l

if you still have the older image on the switch, you can enter in ROMmon mode and force it to boot from the older image.

Otherwise you can get a correct image via TFTP in the ROMmon mode as well. Check the link below:

https://mangattu.wordpress.com/2011/01/03/rommon-recovery-of-3750-x-switch/

[Musole2013]

Thanks @Norberto and @Joseph. Below is the process I followed:

• I interrupted the boot sequence by using the mode button right at the front of the switch.
• I deleted the undesired flash by entering the command delete flash:<ios_name>
• I entered the command boot and watched with glee as the switch booted with the remaining IOS.

Thanks again.

[Joseph W. Doherty · Accepted solution]

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Posting

If you can get into ROMMOM mode, I think you may be able to delete the undesired image.