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Cisco ROMmon and IOS image   Filed Under: Networks

Introduction

This tutorial is a continuation to a previous tutorial about recovery of IOS image using Xmodem connection. This tutorial will focus more on how to go to ROMmon and how to load a different image located in the switch from ROMmon if the one we have is not working.

Going into ROMmon

Routers

To go to ROMmon in a router you will need to restart the router and while the router is loading you need to press the key combination ctrl + break.

Switches

To go to ROMmon in a switch you will need to restart the switch and while is loading you need to press the button on the front of the switch that is labeled “Mode”.

Initialization and loading an IOS image

Once you go to ROMmon the device will present you with a list of available commands:

• flash_init
• load_helper
• boot

Once the ROMmon has loaded you’ll need to execute the command flash_init so you can load the flash memory of the switch (we have the IOS images down there).

After that execute load_helper.

Finally to load the IOS image you want into the switch you need to execute the command

boot <location of the IOS image>

boot flash:/c2950-i6q4l2-mz.121-22.EA2.bin

Changing IOS image

Just to let you know that the command boot from ROMmon will just load that IOS image at that moment if you reboot the switch the switch will start using the previous IOS image it had.

If you want to change the IOS image that the switch will use while loading you’ll need to execute the following command under global configuration mode.

boot system <location of the IOS image>

boot system flash:/c2950-i6q4l2-mz.121-22.EA2.bin

If you want to make sure that the location and the image the switch is going to load is ok you can check this by using the command show boot.

How to know the content and path of a IOS in flash

To look at the content of the flash execute the command

show flash

The flash memory may contain the IOS images inside directories. To check the content of the directory first you need to execute the command cd flash:/<directory>. This will change the present working directory to the directory you have specified so if you issue a show flash the switch/router will show the content in flash of that directory.

If you want to go back to the root of the flash you’ll need to execute the command

cd flash:/