Solved: Cisco 1941 Router iOS Upgrade

Manuel Cruz · ‎02-26-2014

Hi Cisco Community,

I have a question about iOS upgrades for our Cisco 1941 routers. The model spec is Cisco 1941/K9 and we currently are running iOS version 15.1(4)M3.

I know the most recent release is 15.4.1T1(ED), yet one thing i remember from my predecessor is that you want to make the choice to upgrade based on the most stable release with the least amount oif bugs and make sure that your not trading away any crucial features. I was wondering if anyonje had any advice they care to share with me on this situation? I appreciate anyone's input.

Leo Laohoo · ‎02-27-2014

If you want a stable release then going from an "M" train to a "T" train is very risky.

Here's how it goes:

1. A new release is always called as a "General". The IOS does not have any letters at the end.

2. From the "General" release, the developers ADD NEW FEATURES to this release. And they put a "T" at the end of the filename and call it as a "T" train or "T" release. The "T" means Technology.

3. Any bug fixes to the "T" train and the filename gets renamed to become an "M" train. The "M" means Maintenance.

So if you want a stable release, go with the "M" train. The "T" train will always have a higher version and the "M" will always be one version behind the "T" train. This is to be expected.

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Vasilii Mikhailovskii · ‎02-27-2014

Hello, Michael.

Cisco's end-of-life announcement for 15.1(4)M -

http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/ios-15-1m-t/end_of_life_notice_c51-717651.html

Stated:

Customers are encouraged to migrate to the Cisco IOS Software Release 15.2(4)M.

Leo Laohoo · ‎02-27-2014

If you want a stable release then going from an "M" train to a "T" train is very risky.

Here's how it goes:

1. A new release is always called as a "General". The IOS does not have any letters at the end.

2. From the "General" release, the developers ADD NEW FEATURES to this release. And they put a "T" at the end of the filename and call it as a "T" train or "T" release. The "T" means Technology.

3. Any bug fixes to the "T" train and the filename gets renamed to become an "M" train. The "M" means Maintenance.

So if you want a stable release, go with the "M" train. The "T" train will always have a higher version and the "M" will always be one version behind the "T" train. This is to be expected.

Manuel Cruz · ‎02-28-2014

Leo,

Thank you for your response Leo, it was very informative. One more question if you dont mind. I was looking at all T and M releases on the Cisco's site that is available for download. Cisco identifies one with a star as the recommended one for sfotware stability, quality and longevity. Now since I'm 4 versions away, do these iOS upgrades requires every upgrade or can you bypass previous upgrades to achieve the one you want? Ive dealt with some switches that required this sort of thing but i guess it comes down to weather or not Cisco packages previous upgrade softwar einto there recent releases so that they become retroactive to the installation. As always I appreciate your answer.

Leo Laohoo · ‎03-01-2014

Now since I'm 4 versions away, do these iOS upgrades requires every upgrade or can you bypass previous upgrades to achieve the one you want?

No. You don't need "baby steps". You can upgrade DIRECT.

Another thing: Since you are upgrading the IOS (which, obviously, requires a reboot), why don't you upgrade the bootstrap?

Guess what? You can upgrade the IOS and the bootstrap with ONE REBOOT. Here's how you do it:

1. Copy the IOS to the appliance. DO NOT REBOOT THE ROUTER.;

2. [OPTIONAL] Change the boot variable string;

3. Upgrade the bootstrap using the command "upgrade rom file flash:bootstrap_filename.extension"

You will be asked with a "y/n" question and when you hit "y" the appliance will reload and boot into the NEW IOS you've specified.