Router config-register 0xC502

Unanswered Question
Jun 1st, 2010
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Hi All,

I have Cisco 2811 Router and few days ago my router doesn't work correctly. I checked config and found config-register waas changed (0xC502).

HUV_Murun#sh version

Cisco IOS Software, 2800 Software (C2800NM-IPBASE-M), Version 12.4(9)T7, RELEASE SOFTWARE (fc3)

Technical Support:

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

Compiled Thu 10-Jan-08 16:35 by prod_rel_team

ROM: System Bootstrap, Version 12.4(13r)T, RELEASE SOFTWARE (fc1)

HUV_Murun uptime is 23 hours, 36 minutes

System returned to ROM by power-on

System image file is "flash:c2800nm-ipbase-mz.124-9.T7.bin"

Cisco 2811 (revision 53.50) with 251904K/10240K bytes of memory.

Processor board ID FHK1228F2RY

2 FastEthernet interfaces

1 Serial interface

6 Channelized E1/PRI ports

DRAM configuration is 64 bits wide with parity enabled.

239K bytes of non-volatile configuration memory.

62720K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0xC502

Anybody know what is the meaning of this config-register (0xC502) and how can be changed config ?



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Leo Laohoo Tue, 06/01/2010 - 18:59
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how can be changed config

Go to configuration mode and enter the command "config-register 0x2102".

Use of the Configuration Register on All Cisco Routers

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michael.leblanc Wed, 07/14/2010 - 09:18
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Although I have not used it in a very long time, there is a free software utility "Config Reg Calculator" offered by Boson, which "allows you to determine what a router will do given the configuration  register value".

It is available at:

Perhaps it might be of interest to you.

Best Regards,


haneez2949 Mon, 10/22/2012 - 23:16
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config-register (0xC502)  means

C- 15th and 14th bit set

14th-IP broadcasts do not have network numbers

15th-Enable diagnostic messages and ignore NVRAM contents    

5- 8th & 10th bit set

8th-Break disabled

10th-IP broadcast with all zeros


2-Boot field

Thanks and regards.



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