There really isn't a lot to it but since you will probably only do it a handful of times during your career I thought it was a worthy post.
First things that you need to do is download the latest image from Cisco and will look something like this.
C1841_RM2.srec.124-13r.T5
You can check to see what revision your router is running by entering this command:
#show version
Look for this line in the output, it will vary depending on your device and image.
ROM: System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fc1)
We are going to upgrade the current image to (124-13r)
Once you have the file, you need to get it onto your routers flash card or put it on a USB drive.
All you have to do is type this command and thats it.
Router#upgrade rom-monitor file flash:C1841_RM2.srec.124-13r.T5
This command will result in a 'power-on reset' of the router!
Continue? [yes/no]: y
ROMMON image upgrade in progress.
Erasing boot flash eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
Programming boot flash ppppppppppp
Now Reloading
System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2004 by cisco Systems, Inc.
And here we are:
System Bootstrap, Version 12.4(13r)T5, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2007 by cisco Systems, Inc.
Thats it for today!
