Hi, I have 1841, 2800 and 3800 routers and need to do IOS upgrade to all of them. Existing routers do not have enough flash to hold 2 IOS images.
Question: if the router has 12.4.13r ROM IOS, will I be able to boot the ISR router via Cisco brand USB? That means in case something goes wrong while I am uploading new IOS to the router via WAN and something wrong, now router in ROMMON mode. If a local site person has a Cisco USB with an IOS in it, can he just stick it to the router and reboot the router and router will go out of rommon and go into normal mode? After it is working, then I can put the running IOS onto the exisitng CF card so now I can remove the USB and the CF card has a good IOS and reboot the router again.
I am just trying to find a safe way to upgrade the site when they don't have big enough flash to hold 2 IOS at the same time. The local person is not technical so asking him to setup tftp server and put the IOS in the computer and so I can do tftpdnld while in rommon mode to grab the IOS from his tftp will be difficult to have the local person to set it up.
If ISR can boot off of the IOS in USB only, then I assume the requiremetn is the ROM IOS needs to be 12.4.13r. Then what is a safe way to upgrade the ROM IOS to this then? I never upgrade ROM IOS before so don't know what kind of problem I may run into and whether it's higher risk to upgrade this than upgrading the regular ios? If it is, then all my routers won't have this ROM IOS version, so that means I can't use USB to boot then? Will that means I am down to tftp server option? ( I heard xmodem won't work as it will time out before the ios can load via the slow dialup link into the router to rescue it from rommon mode).
"so will that mean even copying IOS from pc to USB directly is still bad?" < --- Files written by a PC can't be read by Cisco appliance because Cisco is using Unix OS.
However I have read about the FAT32 format but I have yet to try it. If you have tried it and it worked, then go ahead with it. :)
"In Plan B Step 4, is there any chance that we can screw up this rommon upgrade and then now my router is really dead and need hardware replacement?"
If the ROMmon file is invalid, the router will reject the upgrade. This is also one reason why I'm reluctant to try the FAT32-format option because I don't want to have a dead piece of brick in my hands. :)
"But do I still have any risk doing Step 4 when I perform that remotely in the remote office to upgrade their rommon?"
Purely optional. Besides, the file verification process won't take 5 minutes to complete.
"For #8 above, I guess I can copy the IOS via the WAN to the old CF if needed, like you said, I only have one slot."
You may have only one CF slot but the 2800/3800 ISR have 2 USB slots.
"The problem is there are many of my 40 routers has 12.1, 12.2 and 12.3 today" < --- How's that possible??? ISR's don't have 12.1 or maybe 12.2 IOS available.