3640 what does config reg mean and why cant I change it ?

[Boettie]

I am trying to upgrade a 3640 , to do voice over IP.First I had problems with the Cisco tftp server,
I could write to the laptop to back up my Image, but when I tried to load from the tftp server , it
always crashed at the same place. Eventually, I simply loadet a new tftp server, from the net.
This time the image loadet ok, verified but when I restarted it, it crashed on me.Started in the
Rmon mode.A collegue from our US office talked me through the process , and we found I can
not change the config-register from its current value of 0x3921. She suggested the 3640 is not
quite healthy . When I got our supplier to send another 3640 , they argued that I should never
need to check the config-register , unless I forgot my password and needet to default or something
like that.
The manual does warn you to check its value through sho vers, but there is also plenty of
write-up about the register affecting password values. All in all Im no wiser and still dont have a working system

who can help

Borttie

 

[ckhanna]

Hi,

Typically, the only time you will need to change your config register is when you are doing Cisco password recovery. Outside that, your config register will never need to change and should always remain at: 0x2102.

I suspect that you may have a corrupt IOS? It's a possibility since your TFTP server kept crashing in the same spot every time. You may consider erasing your IOS completely and uploading it from scratch. Also, make sure you have enough memory for the IOS you are trying to load.


To manually try to change the config register:

(Normal Mode)
conf t
config-register 0x2102
(reload router)

(ROMMON)
confreg 0x2102
(reload router)

Try this... if all else fails, there is always Cisco TAC.


Good luck!

-Charlie

 

[saleen351]

try this

http://www.cisco.com/warp/public/130/sw_upgrade_proc_ram.shtml

 

[LiNuXGuRL]

the only time i had problems with tftp servers was with remote server on unix or linux systems - which requires changes on the unix machine. when i log onto a cisco locally i use solarwinds tftp.

the confreg should only be changed for pw recovery as ckhanna already stated.