Cisco 851 - Power Outage - How to bring back online?

Posted on 2008-06-24
Last Modified: 2010-05-18
I have a Cisco 851 in one of our branch offices.
They have a 2.5 hour power outag last night (Thunder stroms...) and the 851 did not come back online.
After a 2 hour drive to the branch, I discover the router just needed a reload command.

Before I issued the reload command... this is what I saw on the router - see code snippit.

How can I setup the router so it comes back online once power has restored?
(Or was this a oddball flike??)



851 con0 is now available                                 

Press RETURN to get started.                            

rommon 1 >          

rommon 1 > ?            

alias               set and display aliases command                                                   

boot                boot up an external process                                               

break               set/show/clear the breakpoint                                                 

confreg             configuration register utility                                                  

cont                continue executing a downloaded image                                                         

context             display the context of a loaded image                                                         

cookie              display contents of cookie PROM in hex                                                          

copy                Copy a file-copy [-b <buffer_size>] <src_file> <dst_file>                                                                             

delete              Delete file(s)-delete <filenames ...>                       

dir                 List files in directories-dir <directory>

dis                 display instruction stream

dnld                serial download a program module

format              Format a filesystem-format <filesystem>

frame               print out a selected stack frame

fsck                Check filesystem consistency-fsck <filesystem>

help                monitor builtin command help

history             monitor command history

meminfo             main memory information

mkdir               Create dir(s)-mkdir <dirnames ...>

more                Concatenate (type) file(s)-cat <filenames ...>

rename              Rename a file-rename <old_name> <new_name>

repeat              repeat a monitor command

reset               system reset

rmdir               Remove a directory

set                 display the monitor variables

stack               produce a stack trace

sync                write monitor environment to NVRAM

sysret              print out info from last system return

tftpdnld            tftp image download

unalias             unset an alias

unset               unset a monitor variable

xmodem              x/ymodem image download

rommon 2 >

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Question by:edalzell
  • 4
  • 2

Author Comment

ID: 21855172
Here's my config:

Using 2487 out of 131072 bytes


version 12.4

no service pad

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption


hostname cisco581





logging buffered 52000


no aaa new-model

clock timezone PCTime -5

clock summer-time PCTime date Apr 6 2003 2:00 Oct 26 2003 2:00


crypto pki trustpoint TP-self-signed-1595647584

 enrollment selfsigned

 subject-name cn=IOS-Self-Signed-Certificate-1595647584

 revocation-check none

 rsakeypair TP-self-signed-1595647584



crypto pki certificate chain TP-self-signed-1595647584

 certificate self-signed 01 nvram:IOS-Self-Sig#5.cer

dot11 syslog

no ip dhcp use vrf connected

ip dhcp excluded-address

ip dhcp excluded-address


ip dhcp pool sdm-pool

   import all






   lease 365



ip cef

ip auth-proxy max-nodata-conns 3

ip admission max-nodata-conns 3

no ip domain lookup

ip domain name




username edalzell privilege 15 secret 5 $1$0Hom$xcUg7nbkMTI3eXVr/1Mow.

username kcutech privilege 15 secret 5 $1$Fhi9$F3cbQ9EXUdaflf3EuICR1.




 log config







interface FastEthernet0


interface FastEthernet1


interface FastEthernet2



interface FastEthernet3


interface FastEthernet4

 description $ETH-LAN$

 ip address

 ip access-group 100 in

 duplex auto

 speed auto


interface Vlan1


 ip address

 ip tcp adjust-mss 1452


ip forward-protocol nd

ip route permanent

ip route permanent

ip route permanent


ip http server

ip http access-class 1

ip http authentication local

ip http secure-server

ip http timeout-policy idle 60 life 86400 requests 10000


ip access-list extended ACL1

 remark Allow Ping

 remark SDM_ACL Category=1

 remark PING

 permit icmp any any

ip access-list extended ACL2

 remark Any!

 remark SDM_ACL Category=128

 permit ip any any


no cdp run




banner exec ^Cine


banner login ^CWelcome to KCU!



line con 0

login local

 no modem enable

line aux 0

line vty 0 4

 access-class 101 in

 privilege level 15

 login local

 transport input telnet ssh


scheduler max-task-time 5000


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LVL 43

Expert Comment

ID: 21855178
It was a fluke.  Some times the router boots into ROMMON and requires to be turned off and back on again or issued the "boot" command.  I have seen this when there is something plugged into the console port like a  modem.

Author Comment

ID: 21859573
I see.
I turned the power off (using the power switch..) and while still plugged into the console, it still came up with the ROMMON prompt.
Is there anything I ccan do in the future to prevent a 2.5 hour drive? ;-)

Thanks for your help!
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Accepted Solution

fileinster earned 500 total points
ID: 21861534
Yes, try this:
sh ver  (look for Configuration Register near the end)
If it's not 2102 do this:

conf t
config-register 0x2102

Power off the router and see if that helps.


Author Comment

ID: 21861916
Ok... it says: Configuration register is 0x0
What does this do? (I'll try this next time I'm there.....)


Cisco IOS Software, C850 Software (C850-ADVSECURITYK9-M), Version 12.4(15)T5, RE


Technical Support:

Copyright (c) 1986-2008 by Cisco Systems, Inc.

Compiled Thu 01-May-08 02:07 by prod_rel_team

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

cisco851 uptime is 12 hours, 35 minutes

System returned to ROM by power-on

System image file is "flash:c850-advsecurityk9-mz.124-15.T5.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 851 (MPC8272) processor (revision 0x300) with 59392K/6144K bytes of memory


Processor board ID FHK1223201V

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

5 FastEthernet interfaces

128K bytes of non-volatile configuration memory.

20480K bytes of processor board System flash (Intel Strataflash)

Configuration register is 0x0

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Expert Comment

ID: 21867352
AH! that's your problem then. Do what I said and that'll be fixed.

The configuration register specifies where the router gets it's IOS image from. 0x0 means don't boot, while 0x2102 means boot from flash.

Author Comment

ID: 21875315
Great, thanks fileinster!

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