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How to upgrade the Cisco 3750 switches step by step with low memory

This article explains the process of upgrading the Old Cisco 3750 switches that are low in memory and are over loaded.  if there is a troubled switch  where the memory and CPU is spiked, there is workaround you can do to get this upgraded to the stable code. one of the main cause could be 802.1x authentication that will spike the CPU and Memory and will cause the TFTP process to fail

One thing to make sure that anything that is causing the CPU and memory spike has to be disabled for the upgrade to complete

you can do process of elimination until CPU becomes normal, in my case I had to disable 802.1x to get TFTP to copy the IOS to the switch

few important commands to run before the upgrade

show flash: this shows you the available space on the flash – you will need to do this on all the switches in the stack by adding doing sh flash2 and etc


Also run the sh boot command to validate the boot path and you will need to change that again

here are the validation steps

  1.  Verify the OS and make a note of it just in case you need to revert back for any reason like in the previous screenshot by running the show version or show boot


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