Upgrading IOS

Answered Question
Feb 3rd, 2010

I'm trying to upgrade our switch IOS. I used telnet to connect to the device, had setup the tftp server and started the service, the software was in the TFTP root, and typed copy tftp flash. The file copied over without an issue, but I never got the 'erase flash?' question. The current IOS running is in a sub-directory off the flash 'root'. Looking at a document 'Loading Cisco IOS Software', it's mentioned changing the config register to the value 0x2101. Why is that done? Is it necessary in each case?



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Correct Answer by Reza Sharifi about 6 years 8 months ago

Yes, if this is in production, do it during on outage window in case some thing goes wrong.

Also, take a look at the 3560 command reference guide to make sure every thing is correct before rebooting




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Reza Sharifi Wed, 02/03/2010 - 07:45

Hello Chris,

When you have enough space in your flash, it will not ask you to delete the old one. Now that you have 2 images on your flash, make sure you point your boot variable to the new IOS before rebooting.  No need to change the config register value.



Reza Sharifi Wed, 02/03/2010 - 07:58

What type of switch do you have?

it is usually "boot system flash

Then do a "sh boot" and make sure the new image is in the boot variable




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