Can't change config-register on 3725

[gkuzmowycz]

I have a 3725 running IOS 12.3(13b)with a system bootstrap of 12.2(8r)T. After a failed IOS load I had to do a rommon xmodem download of the image. In order to expedite that I changed the config-reg from within rommon to get a port speed of 115200. Now I can't change it back.

IOS is loaded and the router is running. When I go to enable mode and say "config-register 0x2102" it does not seem to "take", since when I exit and save and say "sho ver" it still says "Configuration register is 0x3922". Note the absence of the "next boot" value.

On another 3725 running the same exact IOS I have no problem.

[Richard Burts]

George

I do not want to be picky, but when you say you go to enable mode and say "config-register..." do you mean enable mode or do you mean global-config mode?

I am not sure why changing the config-register from rommon would impact the ability to change it from config mode. Perhaps you could do a screen capture of entering the command and of the show version.

I also wonder what would happen if you went into configuration mode to line console 0 and specified speed 9600.

HTH

Rick

[gkuzmowycz]

Sorry, too abbreviated. I did mean global-config mode.

Here's how it looks when I do it (I changed the router name for this forum)

RNAME#

RNAME#conf t

Enter configuration commands, one per line. End with CNTL/Z.

RNAME(config)#config-r 0x2102

RNAME(config)#exit

RNAME#copy run start

Destination filename [startup-config]?

Building configuration...

[OK]

RNAME#sho ver

Cisco Internetwork Operating System Software

IOS (tm) 3700 Software (C3725-JK9S-M), Version 12.3(13b), RELEASE SOFTWARE (fc2)

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

Copyright (c) 1986-2005 by cisco Systems, Inc.

Compiled Thu 11-Aug-05 13:48 by alnguyen

Image text-base: 0x60008AF4, data-base: 0x62148000

ROM: System Bootstrap, Version 12.2(8r)T, RELEASE SOFTWARE (fc1)

ROM: 3700 Software (C3725-JK9S-M), Version 12.3(13b), RELEASE SOFTWARE (fc2)

RNAME uptime is 20 hours, 6 minutes

System returned to ROM by power-on

System restarted at 17:30:48 EDT Mon Apr 24 2006

System image file is "flash:c3725-jk9s-mz.123-13b.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:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

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

export@cisco.com.

cisco 3725 (R7000) processor (revision 0.1) with 111616K/19456K bytes of memory.

Processor board ID JMX0637LRZZ

R7000 CPU at 240MHz, Implementation 39, Rev 3.3, 256KB L2 Cache

Bridging software.

X.25 software, Version 3.0.0.

SuperLAT software (copyright 1990 by Meridian Technology Corp).

TN3270 Emulation software.

3 FastEthernet/IEEE 802.3 interface(s)

1 Token Ring/IEEE 802.5 interface(s)

2 Serial(sync/async) network interface(s)

DRAM configuration is 64 bits wide with parity disabled.

55K bytes of non-volatile configuration memory.

31360K bytes of ATA System CompactFlash (Read/Write)

Configuration register is 0x3922

RNAME#

[Richard Burts · Accepted solution]

George

Thanks for posting the additional information. I certainly understand wanting to protect identifying information when posting to the forum and changing the router name does not affect what we need to see.

It is interesting that the config-register command appears to be correct syntax but does not have the desired effect. I believe that it is because of another thing that changed when you made the original change. I believe that there is now a speed command under line console 0. Would you check the config of the router and verify whether there is a speed command under line console 0. Assuming that there is a speed command in the config, then you would need to go into config mode and change the speed of line console 0 to 9600.

The config-register value of 0x3922 reflects a console speed of 115200 and I believe that this platform then inserts the speed command under line console 0. As long as the config command for console speed is active, the config register can not be set to 0x2102.

So please check for the existance of the speed command under line console 0 and if it is there change it and let us know what happens.

HTH

Rick

[gkuzmowycz]

Great catch, Rick.

The line con 0 did indeed have a speed of 115200. I changed it to 9600, and then the "sho ver" said "Configuration register is 0x3922 (will be 0x2102 at next reload)".

Thanks.