Right on that makes sense as I have done it before...but not in a good while...just wanted to measure twice and cut once!

Actually I left out something in my initial post.

In what version of IOS did upgrading in this manner become available?

In older versions of IOS was it not possible to upgrade in this way?

If there is a cutoff approx what IOS version would be too old to upgrade this way?

Hi, this does not depend on the IOS version and never did. Just delete old IOS and copy the new one.

Also, IOS never requires progressive upgrades.

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Mark does remember correctly that there was a time when you could not just erase the image and load a new image while the router continued to run. But it was platform based and not version of IOS based. There were some routers that ran the image from flash rather than from RAM. They primary example of this was the 2500 routers which actually had to boot into rommon to load a new image.

There have not been any routers with this restriction in quite a while. So Mark should be pretty safe in erasing the image and copying a new image. There is a bit of exposure in this process - if something happens in the interval between when the old image is erased and the copy of the new image is completed then there is a problem. The suggestion from Amit is a way to provide a bit of a safety net. It requires a bit more effort than just erase the old image, copy the new image, reboot - but it does provide a method that does not leave you exposed. Especially if the router is remote it might be worth it.

HTH

Rick

Thanks everyone for your comments.

I appreciate the input and helpful suggestions.

I will follow the method that Amit pointed out.

GLTA.