IOS checksum error...

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When I boot  my 3640 router this is what happening...(message
below)..then after 2 tries it goes to ROM monitor mode
This is when I use c3640-jk9o3s-mz.124-5a ios or c3640-jk9o3s-mz.
123-13b ios. Ive reinstalled ios many times.
But when I use c3640-is56-mz.112-21.P ios it doesnt create any
problem.
How can I solve this...I also took out ram and flash and cleaned it
but no use....

Any solution I can have...
-----------------------------------------------------------------------------------------------------------------------------------------
System Bootstrap, Version 11.1(20)AA2, EARLY DEPLOYMENT RELEASE
SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
C3600 processor with 131072 Kbytes of main memory
Main memory is configured to 64 bit mode with parity disabled

program load complete, entry point: 0x80008000, size: 0x1b84974
Self decompressing the image :
############################################################################################################################################################################################################################################################################################################################
[OK]

Error : uncompressed image checksum is incorrect 0x90C3C8F1
       Expected a checksum of 0xA8C3FACD

*** System received a Software forced crash ***
signal= 0x17, code= 0x9, context= 0x8000eb60
PC = 0x800080d4, Cause = 0x20, Status Reg = 0x3041f003

System Bootstrap, Version 11.1(20)AA2, EARLY DEPLOYMENT RELEASE
SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
C3600 processor with 131072 Kbytes of main memory
Main memory is configured to 64 bit mode with parity disabled

Re: IOS checksum error...
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###########################################################################=
###########################################################################=
##################
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Clear the memory, redownload the image, check the checksum on the
download (Cisco provides the checksum I thought), transfer to the
memory, modify the boot statement, reboot.

Re: IOS checksum error...
Clear the memory by which command
Im now in rom monitor mode ....or should I install the working ios
thanks for ur help


Re: IOS checksum error...
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I think its something like 'delete flash'.

Re: IOS checksum error...
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Delete command is not there in flash and actually there is nothing in
flash to delete bcoz I install new ios everytime
sono chance there... is there any other way...

Re: IOS checksum error...
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I wouldn't worry about it.  Just redownload the image to your
workstation, check the checksum (make sure its valid at that point),
the resend to the flash.  Not sure what you are using, but I have
experienced issues with checksum issues with some file transfer
servers, so you may need to swap your app out.

Re: IOS checksum error...
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This message is the result of corrupt images on the router.

When you download the IOS image from Cisco there
are various checksums and the file length
shown on the download page.
MD5 is the easiest since there is only one.

http://www.fourmilab.ch/md5/ has a windows md5.exe
and unix source code.
(website is that of John Walker co-founder of Autodesk
and I regard it as reliable.)

You can compare the MD5 produced by the md5 program
with the MD5 that cisco publish to determine if you
have a good image.

Obviously checking the length first is a decent idea.

The usual cause of corrupt images is failure to specify
binary mode when transferring files by ftp, or I suppose
interrupted transfers.

If you suspected a problem with the flash you
could try a format of it. You can also tftpboot
the router without the image on the flash.

When you have copied the image to the router
you can check the image's integrity with

verify <filemane>

Each image has a checksum stored internally
and the router will re-compute the checksum and
compare it with the stored one.


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