Cisco Update ROMMON / Bootstrap

Some IOS releases require a ROMMON upgrade. This example is performed on a Cisco 1841 Router.

The first step is to download the latest ROMMON software:
Official cisco ROMMON download center

The file will be named something like this: C1841_RM2.srec.124-13r.T5

With the #show version command you can check your current version.

We are going to upgrade 12.3 to 12.4, download the ROMMON update and place it on a USB drive (FAT formatted). Plug the USB drive into the C1841 router.


1. Go into the user privileged mode
2.type, upgrade rom-monitor file usbflash0:C1841_RM2.srec.124-13r.T5

The following message will appear:
This command will result in a  ‘power-on reset’ of the router!
Continue? [yes/no]:

3. Type, yes and hit enter.

The rommon / bootstrap is now upgraded to Version 12.4

Comments: 7

  1. […] Update ROMMON / Bootstrap […]

  2. Jason Madruga June 19, 2013 at 02:00 Reply

    Worked like a charm… Thanks!

  3. Morris Gomes August 3, 2013 at 05:53 Reply

    worked on the first try. thanks

  4. Michael March 9, 2015 at 04:32 Reply

    Dude, how about login info?

    • p.vanos March 9, 2015 at 18:02 Reply

      What login info?
      You don’t know how to connect to a Cisco switch?

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