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New Member

877 rommon problem


I have a new Cisco 877 that works just fine for 20mins - 2hours but then fails and enters rommon mode for no reason. Then I can reset it and again it works for a while then goes back into rommon.

Is this something that has been seen before?

I would appreciate any help in fixing this problem.




Re: 877 rommon problem

Might be a buggy IOS that has a memory leak.

The router will reload when all memory is gone.

Also, you should check that the config register is set up to boot the first file from flash.

To give more precise directions, you should post your config and the output of "sh ver".



New Member

Re: 877 rommon problem

Thanks Leo sh ver is as follows -

Cisco IOS Software, C870 Software (C870-ADVIPSERVICESK9-M), Version 12.4(9)T4, RELEASE SOFTWARE (fc2)

Technical Support:

Copyright (c) 1986-2007 by Cisco Systems, Inc.

Compiled Thu 07-Jun-07 14:00 by prod_rel_team

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

NCCSUF01 uptime is 2 hours, 13 minutes

System returned to ROM by power-on

System image file is "flash:c870.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

If you require further assistance please contact us by sending email to

Cisco 877 (MPC8272) processor (revision 0x300) with 118784K/12288K bytes of memory.

Processor board ID FCZ1222137R

MPC8272 CPU Rev: Part Number 0xC, Mask Number 0x10

4 FastEthernet interfaces

1 ATM interface

128K bytes of non-volatile configuration memory.

24576K bytes of processor board System flash (Intel Strataflash)

Configuration register is 0x1

Re: 877 rommon problem

logon to the router and change the Configuration register to 0x2102 and reload.

New Member

Re: 877 rommon problem

Thanks francisco_1

Could you tell me what difference that makes?

Re: 877 rommon problem

Config register

The NVRAM has a special location that contains the 16-bit configuration register. Every time the router boots it reads this value. The config-register value is a hexadecimal value ranging from from 0x0000 to 0xFFFF and can be set byusing the config-register command. The most important portion of the configuration register to understand is the boot field (bit 0 through 3, hexadecimal range 0x0000-0x000F). The boot field value is used to specify from which location the IOS image should be loaded or bypassed even during startup.

Boot field Meaning

0x0 The router will enter ROM monitor mode and remain at the system bootstrap prompt.

0x1 The IOS image stored in ROM will be loaded.

0x2-0xF The router will boot as normal and load the default IOS image stored in Flash and enables boot system commands.

please rate is this helps.

Re: 877 rommon problem

Your IOS seems to be not too recent so it might contain a bug. My advice would be to get an update.

Changing the config-reg to 0x2102 will at least make the router reboot instead of entering rommon.



Re: 877 rommon problem

Cisco engineering has identified some serious software issue with the release 12.4(9)T4 (ADVANCED IP SERVICES) which might be related to the router reload and config-register changes. Suggest you upgrade to at least 12.4.15T5.

Re: 877 rommon problem


do you need help with anything else? if not can you please rate the discussion.