Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member

Simple ISO upgrade question


I will be upgrading an the IOS of a Cisco router via my TFTP server, how can I tell it to use the new one as there will be the new and old one on there? I haven't rebooted it yet and I don't want a rommon prompt which I have heard about :)

Hall of Fame Super Gold

Re: Simple ISO upgrade question

If you have 2 images in flash then you use the boot system command to tell the router which image to boot. By default the router will boot the first image that it finds in flash (which would be the old image usually). The boot system command tells the router which image that you want it to boot. The syntax may vary a bit depending on the model of router and how its flash is identified/named. But the command would look something like this:

boot system flash:

When I do this I frequently put in a boot system command for the new image as the first command and then configure a second boot system command pointing to the old image (just in case there is a problem in booting the first image).



Community Member

Re: Simple ISO upgrade question

Sounds like a good idea, put one first and one second? I only see an option for "boot system flash:" and no way to add 2 then order them?

Super Bronze

Re: Simple ISO upgrade question

Multiple entries should be saved in the sequence you enter them.

If you need to later place a new entry before already recorded entries, you'll need to delete the prior and re-enter all in the sequence you desire.


The IOS might also allow you to define an entry which has the device but no image (file) name. Can be used to select first valid IOS image from that flash device without knowing name.

CreatePlease to create content