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New Member

Simple IOS Upgrade Question

I am running IOS version 12.3(8)T on a 3745 Router that is a voice gateway. My current image is "c3745-ipvoice-mz.123-8.T.bin". I want to upgrade to a more recent and hopefully stable version of code. How do I know which one will work correctly with my config? Can I just look for the same "c-3745-ipvoice-mz..." on version 12.4 train?

Will rate posts.


Hall of Fame Super Silver

Re: Simple IOS Upgrade Question

Hello Michael,

you can use Feature Navigator to compare images

search by image and take the list of features

then make another search using a key feature for your scenario it will provide a list of images in 12.3T and others in 12.4T

the best image is one that can run on your device so use sh ver to take note of how much RAM and the size of your flash

Hope to help


New Member

Re: Simple IOS Upgrade Question


Thank you, this has been very helpful. The only additionl question I have is do I have to compare all of the features of every image or is there a tool that will find exactly the one that works for me?

There are so many different releases, do you try and go always with the latest?


Cisco Employee

Re: Simple IOS Upgrade Question


While it is not required to compare images all the time, it is always a best practice to do compare images before you upgrade/downgrade. This will help you understand what you are getting into and not run into any surprises.

Below is a brief summary of things I do before upgrade/downgrade.

1. Think about the reason for U/D. Is the U/D due to software recycle management, bug, features, etc

2. Use the Feature Navigator posted by Giuseppe and look for the features/minimum code and also use the bug toolkit to look at the bugs/fixed in version.

3. Pick a version of code and compare it to the one that you are currently running.

4. Most importantly, Read the release notes thoroughly and make sure that there is no deprecated commands/features/etc that might impact your environment and then do the upgrade.

And to answer your question of whether "latest is greatest" ;-), I would use the above points in making that decision and upgrade justification. And while U/D, always have a backout plan, if the upgrade does not go smooth and you run into any issues.

Also, look at the software support for the release that you are running and make sure that you save a copy of the current image on a Server for backup purpose.



*Pls rate if it helps*

New Member

Re: Simple IOS Upgrade Question


Thanks from your help. This makes a lot of sense. I am doing to upgrade based on a possible bug fix. With all of the different releases I wish there was a more exact way of upgrading from the existing code, maybe a tool that says "If you run 12.3xyz, you can upgrade to these recent images safely"

Thanks again for your assistance.

New Member

Re: Simple IOS Upgrade Question


I will plan to do the same thing. I plan to upgrade the IOS 12.3 to 12.4(x) version.

I plan to use the PSCP to copy the binary image from the server to the router. My question is that Can you use the pscp command

to copy the binary IOS image to the router's

flash from the window command prompt?

And if so, would you please share w/ me the


Thanks a lot