IOS Upgrade Question

[billmacmillan]

So I really should know this but I am not confident in my assumptions. So I know how the numbering works with IOS versions but where is the line you have to use an intermediate version to get to your end version goal? So currently I want to go fro 15.1(2)SY2 up to 15.1(2)SY11 and in my mind when dealing with just rebuilds within the same Major/Minor version I can go directly to 15.1(2)SY11. Is my assumption right? Is there a chart or document outlining the rules for version upgrades.

[dperezoquendo]

Hello,

You can refer to the following as an example: https://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/ios-software-releases-12-4-mainline/prod_white_paper0900aecd805079fb.html

Only upgrade path I'm aware of for Cisco IOS is 12.4 to Release 15.0(1) or later releases. 

[billmacmillan]

Just so I am stating this clearly, I am already at 15.1(2)SY2 and the plan is to upgrade to 15.1(2)SY11. Pretty sure I can do this directly and just looking for confirmation.

[dperezoquendo]

Yes, I'm am pretty sure as well. Just in case, I've reviewed the release notes: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/15-1SY/release_notes.html and I couldn't find anything that would prevent you from jumping to 15.1(2)SY11.

[Reza Sharifi]

It should not be an issue to go directly to 15.1(2)SY11.

HTH

[Leo Laohoo · Accepted solution]

Read the Release Notes to the version you want to go to. The Release Notes would normally highlight if you need to jump to an intermediate release or not.
Most of the time for routers and switches, it is fine to go straight.

[Joseph W. Doherty]

As Leo notes, the release notes should indicate any intermediate IOS versions that must be applied to move up to a certain IOS version.
As he also notes, you rarely encounter this, but when you do, if often is due to syntax changes in the configs and/or firmware updates.
Also, the release notes might note special issues if you try to downgrade. When such are not noted, you can still run into issues with syntax changes. (I.e. if you want to be able to back out an IOS upgrade, good idea to save a copy of the config that was actually being used by the original IOS version.)