IOS Upgrade path for Catalyst 6509 (Route Switch Module)

[rvaccare]

I am looking at a Catalyst 6509 switch with the route switch module, running IOS 12.1(2)E. However, I do not have an understanding of the IOS upgrade path in this instance. Specifically, does the upgrade have to follow the 12.1(2) path (for example, would the next upgrade be to 12.1(2)E1)? Or does the upgrade have to follow the 12.1(#)E path (for example, would the next upgrade be to 12.1(3)E)? Or does none of this matter (for example, the next upgrade could be 12.1(23)E1, which is the latest 12.1 release, or could the switch be upgraded to the most recent 12.2 release)?

Thanks for any help you can provide regarding the convoluted Cisco upgrade path.

[Prashanth Krishnappa]

12.1(13)E train has lot of bug fixes and security vulnerability fixes. 12.1(13)E15 is the latest at this time. You can directly upgrade to 12.1(13)E15 from 12.1(2)E. Release notes are at

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/relnotes/ol_2309.htm

If you have MSFC1, it cannot run 12.2 code

[smif101]

The IOS version can be upgraded to the latest release even if you are at 11.3 or 12.1. For the 6500 SUP720/MSFC3 the latest is 12.2.18. The only time you need to upgrade your IOS is one, when you have a bug with software release and an update is out there to fix it. Two, is if there is a security update that needs to applied. Three, if you need to add new features for you router. If there is no problems with your current IOS then upgrading to be upgrading is not something you should do, it could only cause problems. The different versions has various bug fixes and software features implemented in them.