show version will show you the reason of the last reload. Exception crashinfo is configured as default for a few years. If there is no crashinfo in the flash:, it is another place to find out why the device reload.
Below is sample from my lab router:
Router uptime is 1 day, 21 hours, 6 minutes System returned to ROM by power-on
Well you can divide whole upgrade process in three parts:
1- Planning 2- Preparation 3- Execution
Planning includes consideration of which IOS suitable for your device according to services you are running and after deciding list of IOS, query for bug present in current IOS. And make your final selection where you find less no. of bugs according to services you have deployed.
Preparation includes deciding date/time, Download IOS on local machine and Memory audit of available memory on device against size of IOS, verifying md5 value once IOS is dumped on device against value supplied on cisco site.
Execution includes checking for config-register/follow proper upgrade process/be ready for dumping IOS via. console as a disaster recovery.
If you have big network you can plan some pilot node and replicate he same in entire network based on results of pilot.
There is no single doc. which talks all about, Below doc. will be helpful for upgrade process.
I am getting confuse about cisco IOS related issues.
Can u help me regarding the above means ,How can i troubleshoot if IS crashes or How can i get IOS compatibility features or supporting features
and The prerequisits before going to upgrade IOS ,and many things.
Can anyone send the appropriate and best document of the above to get the Idea.
As suggested by other always check the compatibilty of ios using feature navigator and check the realase notes for the same before doing upgarde process.
Better recommendation is used to go through realease note of the ios which can brief some the facts about the same like below link is the realase note on Cisco IOS Release 12.2(55)SE which give a clear picture about the ios feature and requirement.
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