Upgrading IOS image

[christopher_hall]

Hello group,

I'm in the process of upgrading IOS image on Cisco 1811 routers. The first router I've checked for free space shows there's not enough (and I'm sure the others will be the same). I was curious to find out if during the process (I'm using a TFTP program and will upgrade through that) if I'll be able to erase the existing IOS or if there's another recommended process to as to not lose the existing config or cause any downtime. I'll be completing this after hours.

Thanks,

Chris

[daniel.dib]

The IOS image is loaded into RAM. If there is not enough space to hold both images you will have to delete the current one and then upload the new one.

Make sure that you have a stable power source since if the device were to reboot before you have completed upgrade you would have no valid IOS to boot from.

Daniel Dib
CCIE #37149

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[Leo Laohoo]

The first router I've checked for free space shows there's not enough (and I'm sure the others will be the same).

No issues.  You either clear out the useless stuff in the CF or you go to your nearest electronics or camera shop and find a CF with bigger capacity (up to 4 Gb).

Make sure you use the router to format the new CF before you put any IOS in.  To make it even faster, if your computer has a multi-card reader you can transfer the IOS from your computer to the new CF faster using this method.

If you also have access to the download page, don't forget to upgrade the bootstrap of your router.  The router has, if memory is still correct, two USB ports.  If you upgrade your bootstrap this will enable you to boot an IOS using USB thumb drive.