Planning IOS upgrade: how to discover which features are needed?

Aliaksandr Tratseuski · ‎04-30-2015

Hi folks!

The case:

I plan to upgrade an IOS on my ISR 2921 from 15.1(4)M4 to some more recent. I went to cisco.com and saw lots of new versions to download. Then selected one and went to Cisco Feature Navigator (CFN) to discover if the new image supports e.g. IPsec (just for example). The option Compare Images was selected and CFN output was:

Features unique for the first image (my current)
Features unique for the second image (planned)
Common features

The question:

How do I find out that I currently don't use any unique features of the first image? Is there some command for CLI to view names of all currently used features?

I need that in order all config would apply correctly to the new image. I don't know all the features of IOS that's why there is a risk I miss some current feature/technology and problems after an upgrade would arise.

I know that there is a "View Desc" button with a brief explanation of the selected feature, but anyway =)

Thanks!

johnlloyd_13 · ‎04-30-2015

hi,

you'll need to buy and install a security license from cisco for IP sec feature to be supported on your 2921.

Aliaksandr Tratseuski · ‎04-30-2015

Yeah, you're right. It's installed.

IPsec was just as an example. You may imagine any feature you need.

The question is not in how to enable some new features but how not to loose features used in old release.

johnlloyd_13 · ‎04-30-2015

hi,

you'll need to check and compare them on cisco's feature navigator site:

www.cisco.com/go/fn

dhopfmueller · ‎05-01-2015

Aliaksandr,

I don't know of any automated method. Since the number of unique features of the older version is probably managable I'd check the running config for related entries.

Ideally you have a second identical device that's not in productive use that you can use for prior tests. If not I suggest keeping the current image at hand (on the device, if memory allows, or at least downloaded on your computer) to be able to quickly downgrade in case any troubles arise.

Good luck!