Downgrading a c3750X to IOS 12.2.55-SE8

[Lorenzo H.]

HI guys, I couldn't find a page with a breakdown of features I'll lose when downgrading from IOS 15 to 12. Do you guys know what features I'd lose/gain or point me on the right track?

Thanks.

[Reza Sharifi · Accepted solution]

Hi Lorenzo,

You would need to go through the release notes and look at the major sections.  A lots of changes are bug fix related, so you may not loose any feature.  I don't remeber a significant feature that is in IOS 15 and not in 12.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_55_se/release/notes/OL23053.html

for 15

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/15.0_1_se/release/notes/OL25302.html

HTH

[Leo Laohoo]

Before you downgrade from one bad IOS version to another bad IOS version, what is your CURRENT IOS version?

[Lorenzo H.]

I was going to install the latest IOS 15 version as opposed to the factory shipped image which i believe is 12.2.55-SE5.

So technically i'm still upgrading the switch but since my boss wanted it to run the latest IOS version I wanted a breakdown of bugs/features present on both versions.

[johnnylingo]

Sooooo out of curiosity why are you looking to downgrade? High CPU?

I don't know offhand of any major features in 15 not in 12. Something to watch out for is the microcode will be downgraded in the process, and that takes about 25 minutes. So expect 30 minutes of downtime for the switch

Sent from Cisco Technical Support iPad App

[Leo Laohoo]

Something to watch out for is the microcode will be downgraded in the process, and that takes about 25 minutes. So expect 30 minutes of downtime for the switch

I've downgraded from 15.0 to 12.2(55)SE7 and I've never seen a microcode downgrade before.

I don't know offhand of any major features in 15 not in 12.

You remember those scary stories your parents tell you before you go to sleep and keeps you up all night?  IOS version 15.0 is much, much worst than those scary stories.  Currently, 15.0(2)SE4 is looking like a "mature" version.  Any versions  is something to avoid like a bad case of the flu.

Personally, I wouldn't install any 15.0 IOS (execpt for the SE4) in the network unless tomorrow is your last day. 

NOTE:  Hence, the reason why I am keeping 15.0(2)SE3 in my files.  LOL!

[murphy_john]

Old post but figure worth mentioning..  I had to add a switch to an old stack and downgrade from 15.2 to 12.2 before adding and it absolutely does microcode programming so plan for the extra time.  

[Joseph W. Doherty]

Just to confirm, you saw a microcode upgrade on an IOS downgrade?

Hmm, I wonder if such a microcode "upgrade" actually downgraded the microcode.

[murphy_john]

What I witnessed was a very long microcode “programming” when going from the 15 to the 12.2 in About 25 minutes but I did not time it.

I would assume if it had to do that it was downgrading microcode to meet the 12.2 specification.

Another switch setup was a minor upgrade from 12.2(55) se5 to 12.2(55) se6. That one was completed much faster without the programming and up in about 5 minutes.

Regards,
John Murphy

[Lorenzo H.]

The reason behind this is because i will mix 3750x and 3750 on a switch stack and as you know they need to be running the same IOS versions.

I didn't see IOS 15 available for the 3750 but after you guys have said about that version I'm not even interested on it anymore lol

[sgouldbo · Accepted solution]

Hello,

For future reference...

You can use the feature navigator to compare features between two images:

http://tools.cisco.com/ITDIT/CFN/jsp/compareImages.jsp

Regards,

Sony

[Lorenzo H.]

Sonywen Gouldbourne wrote:
Hello, 
For future reference...
You can use the feature navigator to compare features between two images:
http://tools.cisco.com/ITDIT/CFN/jsp/compareImages.jsp
Regards, 
Sony

This tool is awesome! Thanks bunch.

[Leo Laohoo]

I didn't see IOS 15 available for the 3750

Most likely because your 3750 only has 16 mb flash.  IOS version 15.0 is supported on models with 32 mb flash.

If you have at least one 3750 in a stack and with 16 mb flash, then I'd recommend you use 12.2(55)SE8.  Starting from 12.2(55)SE7, this version is considered (in my books) as one of THE MOST STABLE/mature IOS I've ever come across. 

[huangedmc]

We had a pair of 3750G's running stable forever, even w/ an old version of 12.2(44)SE5.

A colleague just replaced one of them w/ 3750X, (3750G reached EoX status) running 15.0(2)SE2.

We don't do anything fancy...just BGP & HSRP.

After the switch replacement, HSRP would flap every 60 minutes, which is driving us crazy. (HSRP peer w/ the remaining 3750G, which is to be replaced next week)

We didn't change any config between the old & new switches - straight up copy & paste...WTF?!

Our plan was to run a SPAN, and see which HSRP hello's were missed/dropped, but if the switch is dropping the hello's, the SPAN data probably isn't reliable either.

We'll probably rollback the change, and put the old 3750G back in place, or downgrade to 12.2(55)SE8 per Leo's advise.