Cisco router boot up with blank configuration

If your Cisco router (76XX, 72XX, 36XX, 28XX, 18XX) boot up with blank configuration instead of  the original configuration after the power outage or reload, the problem most likely is the router register number is not correct.

Troubleshooting:

Issue command show version to see the what configuration register is. the partial output of show version is below (using Cisco 7604VXR as a example):

<<<===== no related output doesn't list here ======>>>

497448K bytes of Internal ATA PCMCIA card (Sector size 512 bytes).

Configuration register is 0x2102

<<<===== no related output doesn't list here ======>>>

Correct configuration register number should be 0x2102.  If you see the different configuration register number in you show version output, using the below process to correct it.

1. Issue below command in router configuration mode to change the register number to 0x2102:

Router(config)#  config-register  0x2102

2. Issue show version to in privilege mode verify what register number will be at next reload.  partial show version output is below:

<<<===== no related output doesn't list here ======>>>

497448K bytes of Internal ATA PCMCIA card (Sector size 512 bytes).

Configuration register is 0x8002 (will be 0x2102 at next reload)

<<<===== no related output doesn't list here ======>>>

3. Issue the below command in privilege mode to reload your router:

Router#  reload

Router will ask you whether save the configuration after you issue the reload command,  type no.  Don't save the configuration in this case.  if you save running-config  to startup-config, the original configuration will be overwrite by blank configuration.

After reload without save configuration, the router will boot up with original configuration.

For Network Design, Build and Consulting Services, 

please visit:

www.unistreamnetworks.com