Downgrade Cisco 4K IOS-XE 17.3.x > 16.12.x

[johnlloyd_13]

hi,

i got a new 4k router with IOS-XE 17.3.x and would like to "downgrade" to our standard code 16.12.x

both code have smart license enabled. i haven't registered the 4k to smart license server/CSSM.

my question is, is it "safe" to downgrade? or will this corrupt the smart license currently installed?

[marce1000]

                                          >...and would like to "downgrade" to our standard code 16.12.x
 - Unless you have specific requirements or configuration directives  for that release , I advice against doing that , especially if it is a new device. Cisco may have installed that release for specific purposes (hardware compatibility , rommon , other components) , it is then better to keep that release and look for upwards-advisory releases such as : https://software.cisco.com/download/home/286006221/type/282046477/release/Bengaluru-17.6.3a and https://software.cisco.com/download/home/286006221/type/282046477/release/Amsterdam-17.3.5  , only downgrade when really needed , but be aware of the possible mentioned side effects , 

 M.

[Leo Laohoo]

Won't make any difference, pre.  Smart License starts from 16.10.1.  As long as the firmware has Smart License, the Smart (Licensing) Agent will memory leak and it does not matter if it is on 16.12.X or 17.3.X, 17.6.X, 17.9.X or 17.12.X.

[johnlloyd_13]

i did the "downgrade" and made the UC perpetual license to EVAL.

now i have to register the 4K router to CSSM and "authorized" the UC license.

smart license is such a pain to do.

[Leo Laohoo]

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@johnlloyd_13 wrote:
smart license is such a pain to do.

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Unfortunately, CSL is a gift that keeps on giving.  It is not that simple to turn off.  It runs in the background and memory leaks.