What does the version statement do in startup-config?

Answered Question
Sep 17th, 2010
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What is the reason for the verison statement in the startup-config file?  Is it used by the loader to choose the correct IOS?


example from startup-config file

!
version 12.2
service timestamps debug uptime
service timestamps log uptime

!


Thank you.

Correct Answer by Nagaraja Thanthry about 6 years 8 months ago

Hello,


The version statement is used by the IOS to determine the compatibility of the saved configuration file that will be loaded when the device boots up. Sometimes, if you save the configuration using a different IOS train (say 12.3) and boot the device with IOS 12.2, some commands may not be compatible. In that case, the router will display a warning message and that determination is done based on the version information.


Hope this helps.


Regards,


NT

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Correct Answer
Nagaraja Thanthry Fri, 09/17/2010 - 07:04
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  • Cisco Employee,

Hello,


The version statement is used by the IOS to determine the compatibility of the saved configuration file that will be loaded when the device boots up. Sometimes, if you save the configuration using a different IOS train (say 12.3) and boot the device with IOS 12.2, some commands may not be compatible. In that case, the router will display a warning message and that determination is done based on the version information.


Hope this helps.


Regards,


NT

j.shekarchi Fri, 09/17/2010 - 07:11
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Thank you very much for your prompt and informative reply.  Can you point me to any Cisco documentation that discusses this issue?


Thanks again,

John

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