IOS Upgrade

Unanswered Question
Jan 5th, 2009

Hi all,

I have loaded the "s72033-boot-mz.122-33.SXI.bin" file in the 64MB bootflash of Sup720. I also specified the bootvar to boot it from this location and file via boot command.

However, every Sup720 reboot returns to ROMMON mode. Why is that? How do I load this boot image?

I want to use this boot image as the backup image just in case the main IOS is corrupted during copying/transferring.


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Jon Marshall Mon, 01/05/2009 - 14:32


Is the confreg set to 0x2102 ?

If so when the switch is booted up, assuming you can boot with existing IOS can you paste output of

dir /all

sh boot


sh run | include boot system


Richard Burts Mon, 01/05/2009 - 14:34


It might help us if you could supply specifics about how you have configured the Sup720 to boot. But it sounds like your primary boot statement is to boot s72033-boot-mz.122-33.SXI.bin as the primary image. But this is a boot image and not a regular image. When you boot a boot image you go into rommon - that is part of what boot images do. Your primary (or first) boot statement should point to the regular image that you want the Sup720 to run, and you might have this as a second boot statement.


Rick Mon, 01/05/2009 - 15:01


Yes, I have configured boot s72033-boot-mz.122-33.SXI.bin as the primary image. I was simulating if the regular IOS is not there or not bootable, Sup720 would fail back to this boot image. I can configure the regular IOS on the first line without installed on the CF, I don't think it is going to make any difference.

Even in the ROMMON mode, I have tried to boot the boot image without success. Do you know how to boot this image?

Richard Burts Tue, 01/06/2009 - 07:35


What do you expect the result to be when you boot the boot image on the Sup720? I get the impression that you might expect it to run like a regular image. But that is not what boot images do.

You wanted to simulate the problem when the primary image is missing or corrupted. And it sounds to me like you have simulated it very well. When the primary image is missing or corrupted the boot image takes you to rommon so that you can recover and load a different image.


Rick Tue, 01/06/2009 - 09:11


As I remembered it long time ago from somewhere, a boot image is a scale down "mini" version of regular IOS that enables us to perform minimal configuration, such as putting an IP address on an interface, etc.

The prompt of a boot image should be the same as a regular IOS, not ROMMON prompt (at least that's what I have remembered). I don't believe I boot it to the boot image. Rather, the ROMMON prompt was from the switch processor's ROMMON image.

What I expect to see is to boot to the boot image with the enable/privi prompt and allows me to perform tftp, ftp, configuring IP address, the most basic network setup to get me running in case the regular IOS is missing or corrupted.

I believe I found a reference to that boot image. It is called Universal Boot Loader (UBL) image now. However, I cannot find any reference on how to boot to or use this UBL image.


This Discussion