Upgrading IOS on 1841

I'm trying to upgrade the IOS on a 1841 router. Since I'm not a Cisco whiz I thought I would check here to make sure I'm not screwing things up beyond repair.

Current version is 12.3(8)YG Upgrading to 12.4(11)T Device has 128M RAM (116736/14336) Flash has 32M

There is not enough room on the flash card for both images currently. Not sure what all of the other files are but will leave them alone.

I have a couple of options: Try replacing the image on the flash card with the newer one... or Boot via TFTP and make sure everything works before replacing the image.

I'm not sure of the safest method. I think I know how to do either but don't have a clue how to recover if I screw things up.

Here's the plan for replacing the image... Backup current IOS image and config (already done) Delete current image from flash to make room for the new image. (delete flash:/) Copy new image to flash. (copy tftp: flash:) Change the boot config. (boot system flash ) Copy running-config to startup-config. (copy run st) Issue reload command.


Change the boot config. (boot system tftp ) Copy running-config to startup-config. (copy run st) If things work correctly, replace the image using the above procedure.

Am I completely clueless or will this work? How do I recover if things go bad?

Searching the Cisco website is like the proverbial needle in a haystack. If anyone can point me to a place with the info I need that would great. I've searched but everything seems to point back to Cisco.

Thanks, Larry

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You can use either way. Booting from TFTP will give you a "warm and fuzzy feeling" that new IOS is working fine. At the same time you can format your flash, copy a new image, and set a local IOS file as a first in the sequence, and use TFTP Boot option with an old IOS as a fallback.

By the way, why don't you try a "Cisco Network Assistant" to upgrade your software? It works good for me...

Good luck,


------ Cisco IP Phone Headset Adapters

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Hi Larry,

Restrictions for Upgrading the System Image:

Cisco 1800 series routers support only external compact flash memory cards.

Internal flash memory is not supported.

For more details, see:

Troubleshooting and Maintenance: Using CompactFlash Memory Cards

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as well as Cisco 1800 series routers - Troubleshooting and Maintenance: Upgrading the System Image:

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Larry, hope this helps.

Brad Reese Cisco Resumes

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There are a number of issues here.

Firstly, do you need to change the software? If it's working then leaving it as it is, may be worth considering.

  1. The T train is likely to be less stable than the mainline
12.4 e.g. 12.4(12) or 12.4(10)b. I would never use the T train unless I needed its features.

Unless yo have console access to the router then there is always going to be a risk associate with this process. If you have console access then you can always recover.

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to describe recovery.

If you are going to do it remotely check the md5 of the image before you send it to the router and before rebooting it check the image with a verify some.file command.

Also worth checking the file length on sh flash.

You need a backout plan. If you can't visit site then you need to consider vary carefully the driving force behind the proposed change.

If the router is remote, one solution might be to send a flash card to site and get a local to swap the card. If it doesn't come up then simply swap back.

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Larry wrote in news:Xns98C592EAA83D1none@

All good responses... exactly what I was looking for but was unable to find. Seems at though my fail-safe is to boot from the image on the flash with the option of booting from TFTP if it fails. Worst case, ROM Monitor will allow me to restore the old image if necessary.

Thanks again. Next round is on me...


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I have never had a problem deleting the existing version of flash and other files SDM to enable me to replace with a new IOS. Of course after deleting the existing IOS don't reboot ;- )

Should anything happen you can always do a tftpdnld to upload a new IOS from rommon



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Darren Green

Another possibility is to use a PCMCIA CF adapter to copy the IOS on the CF with your PC.

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