I was recently tasked with upgrading all the IOS on our ASRs as we move over to running PFRv3. Like most any other cisco router upgrade the process is pretty straight forward but there are a few caveats in the syntax used on the ASRs. For those that may have never performed a IOS upgrade I will run through the entire process.
Check the current IOS Version
Like any upgrade you need to know where you are starting to see what is going to be needed to get you to where you want to be. If you are jumping several versions of major code then you may need to upgrade to an intermediate code in between to get to the final version you wish to run.
Run a show version
Running the “show version” command will provide you the current system image file that your ASR is running.