Not able to enter Rommon mode with Cisco 870 series

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Mar 23rd, 2009
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Hi All,


I'm trying to enter Rommon mode on a Cisco 870 series Router. This is to recover a corrupt IOS image.


Basically when I send Break during boot, it just cycles the System Bootstrap instead of entering Rommon mode.


I am using TeraTerm and sending Alt + B. I've also tried with HyperTerminal and sent CTL + B, but get the same outcome.


Does anybody know if the procedure is different on 800 series routers? It doesn't appear so from looking at other bits of info.


See below for the output whilst booting:


System Bootstrap, Version 12.3(8r)YI4, RELEASE SOFTWARE

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 2006 by cisco Systems, Inc.


C870 series (Board ID: 1-148) platform with 131072 Kbytes of main memory


Booting flash:/c870-advsecurityk9-mz.124-15.XY3.bin


'Here is where I sent the Break, which causes Bootstrap reload'


System Bootstrap, Version 12.3(8r)YI4, RELEASE SOFTWARE

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 2006 by cisco Systems, Inc.


C870 series (Board ID: 1-148) platform with 131072 Kbytes of main memory


Booting flash:/c870-advsecurityk9-mz.124-15.XY3.bin


Error : compressed image checksum is incorrect 0x4DCCADCB

Expected a checksum of 0x8F526C45


*** System received a Software forced crash ***

signal= 0x17, code= 0x5, context= 0x0

PC = 0x0, Vector = 0x0, SP = 0x0


TIA


Kevin

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falain Wed, 03/25/2009 - 08:38
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on Teraterm, how do you send a ctrl-Break ?

I only know that Break is sent with Alt D but it doesn't work

a.alekseev Wed, 03/25/2009 - 11:24
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just press two keys "Ctrl" + "Break"

falain Wed, 03/25/2009 - 12:14
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I know the Ctrl Key but the Break key doesnt exist !

On Teraterm, you must press Alt B to send a break

and Ctrl Alt B doesnt work

a.alekseev Wed, 03/25/2009 - 12:21
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power off

connect a console cable

set speed in terminal - 300

power on

wait 1 minute

change speed in terminal to 9600


you should be in rommon

falain Wed, 03/25/2009 - 08:42
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Sorry, I would say Alt B not Alt D


Ctrl Alt B doesnt work

falain Wed, 03/25/2009 - 08:34
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I just have the same pb with a Cisco 857

If I send a break (Alt-D with Teraterm), it reboots but when I leave it cooting, I have:

C850 series (Board ID: 2-149) platform with 65536 Kbytes of main memory


Booting flash:/c850-advsecurityk9-mz.124-15.T3.bin


Error : compressed image checksum is incorrect 0x972A2B28

Expected a checksum of 0xC6EA1672


*** System received a Software forced crash ***

signal= 0x17, code= 0x5, context= 0x0

PC = 0x0, Vector = 0x0, SP = 0x0



Don't what to do

tnetusa123 Wed, 03/25/2009 - 08:43
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just change the boot order;

(conf)#config-regiter 0x0


reload

falain Wed, 03/25/2009 - 10:26
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I just said that I cannot issue anything

I can't break boot sequence

kgreenway Wed, 03/25/2009 - 12:44
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I found my problem in the end.


Cannot remember the exact article on Cisco website but a command had been applied which prohibitied me from entering Rommon. Removing the flash completely erased config, etc which was blocking me in the 1st place.


Powered off the Router, removed the Flash, powered up the Router. Router failed to boot without flash, but I was able to enter rommon mode.


Powered off, reinserted Flash. Powered up, Entered Break during boot and straight into Rommon. I was then able to recover IOS using tftdnld.


Hope this helps you too.


Thanks,


Kevin

thotsaphon Wed, 03/25/2009 - 12:45
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Kevin,

5P! Good job!


Toshi

Leo Laohoo Wed, 03/25/2009 - 15:31
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Hi Kevin,

This will work if your appliance has a removable compact flash. The problem is the 870 router doesn't have this luxury.

Leo Laohoo Wed, 03/25/2009 - 15:32
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Hi Kevin,

This will work if your appliance has a removable compact flash. The problem is the 870 router doesn't have this luxury.

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