Cisco – Why did the Cisco router hang

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We have a Cisco 1841 in our storage IDF that was originally running a 12.4(1) IP-BASE image; I wanted to upgrade to an advancedservicesk9-mz image, but the flash did not have enough space, so I deleted the running image. Later I tried inserting a larger CF from a Catalyst4500, which crashed the 1841 router (now without a bootable image).

Using another 1800 series router, I loaded the 12.4(25g) advancedservicesk9 image and verified the image checksums. I set the confreg to 0x2102 from rommon and booted the new image; however the 1841 now hangs indefinitely after printing the IOS export control banner.

I have tried four other images, all with the same results. What is wrong with this router?

UPDATE 1:

I tried loading images from a FAT16-formatted USB, but this didn't work either.

I also tried tftpdnld from rommon, but got a get_mac_address(): Search T_IDPROM_MACADDR (0xc3) failed Illegal MAC address. error and the file would not load.

Best Answer

The problem wound up being a corrupted cookie in rommon... Cisco IOS uses a hidden cookie value to derive the mac-address and serial number for the chassis. If the cookie is corruped, IOS cannot finish loading... all ff values below is obviously corrupted.

This site has more information about how the rommon cookie works; however, Cisco TAC says that changing the cookie is not supported on 1800 series routers and an RMA is the only real solution.

rommon 9 > cookie

cookie:
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
rommon 10 >
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