Problem with Cisco 2521: Cannot startup the router with normal image

Unanswered Question
Feb 19th, 2007

Hi: I know this is an older router but I am using in my lab for testing purpose.

Origianally I had a problem upgrading the IOS image because I received message from the router saying the system flash not writable. So I found the article describing what to do to make the falsh writable: (the articale basically instructed me to use a configure-register 0x2102, it went on to say that after I reboot without saving the flash should be put back to the read-only mode) Well I followed the instructions but I could not copy the new IOS image from my TFTP server to the router, because it kept telling me that no protoco available. So i use the following command (no configure-register 0x2102). Now all I have is a > sign and none of the normal IOS command lines are working. Anybody with any idea how to fix this? I appreciate your help in advance.



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Richard Burts Mon, 02/19/2007 - 09:16


I am not clear whether you get into rommon because of the config register setting or because you have erased the existing image and not got the new image into flash yet. Setting the config register to 0x2102 and booting is a good start. It may fix the problem but if it does not then we may need to figure whether you have any valid image in flash.



ahmednaas Mon, 02/19/2007 - 10:18

The original poster said he used "no configure-register 0x2102". I do not know what negating the config-register command does. Does it reconfigure with the previous value? I don't have a router available to test it.

ahmednaas Tue, 02/20/2007 - 13:07


I tested the "no config-register 0x2102" and it sets the register to 0x0 on the next reload.

Richard Burts Tue, 02/20/2007 - 13:12


That is good to know. And it suggests that assuming that they have not done anything else to the image in flash, that they should be able to do a boot from rommon and get back to normal operation. If they get back to normal operation it might be easier to set the config-register to normal 0x2102 in config mode that to modify it in rommon.



jain.nitin Tue, 02/20/2007 - 22:40

Hi, If you r in rommon > mode & if u have not deleted the image then just say boot, router will boot from any available image then after booting u can change the config-reg parameters.

If it helps do rate it.


proteksa2006 Wed, 02/21/2007 - 10:52


you are in rom monitor mode

type this command:

>o/r 0x2102(press enter)

>i (press enter)

the router must reload,This step causes the router to load the Cisco IOS software from the Flash with the configuration from NVRAM

sorry for my english.

if this don,t work type


post the data please

I hope this could help you.



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