Cisco Routers - Saving Configuration

Cisco Routers - Saving Configuration

Restoring Factory Defaults

1. Issue "show version" command, the configuration register should be 0x2102. You could get something similar to this:

   Cisco IOS Software, C181X Software (C181X-ADVIPSERVICESK9-M), Version 12.4(6)T10, RELEASE SOFTWARE (fc4)
   . . .
   Configuration register is 0x2142

2. Pay attention to the "Configuration register". It should be 0x2102. If the configuration register is different (e.g. it is 0x2142 or anything else), then your box will not restore its configuration upon restart. This can be fixed - see Subsection Setting the Correct Configuration Register below.
3. Execute these commands:

   configure terminal
   config-register 0x2102   
   end

4. Erase the existing configuration:

   write erase

5. Issue "reload" command, do not save the configuration, confirm (i.e. press Enter key next to the "[confirm]" message without typing anything).

Simple initial configuration

1. Execute the following dialog, by answering questions as shown below:

   Would you like to enter the initial configuration dialog? [yes/no] yes
   Would you like to enter basic management setup? [yes/no] yes
   Enter host name [Router] R1
   Enter enable secret: (something)
   Enter enable password: (something-else)
   Enter virtual terminal password: (something-else)
   Configure SNMP Network Management? no
   Enter interface name used to connect to the
   management network from the above interface summary: FastEthernet0
   Use the 100 Base-TX (RJ-45) connector?:  yes
   Operate in full-duplex mode: yes
   Configure IP on this interface? yes
       IP address for this interface: 172.17.120.21
       Subnet mask for this interface: 255.255.255.0
   [0] Go to the IOS command prompt without saving this config.
   [1] Return back to the setup without saving this config.
   [2] Save this configuration to nvram and exit.
       [press "2"]
   Press RETURN to get started!
       [press "Enter"]

Saving configuration

1. To save configuration locally (to NVRAM), type this command:

   copy running-config startup-config

2. To upload configuration to an TFTP server, enter:

   copy running-config tftp

   For this command to work, feel free to install "3CDaemon" Windows software (or any Linux TFTP server), and disable firewall.
3. If you have changed configuration and issue "reload" command, they may ask, if you want to save the configuration (this would change the starting configuration). If you do not wish to save anything (and want to return properly to the initial setup), say "no".

Setting the Correct Configuration Register

One of the reasons why the router can bypass the startup configuration stored in NVRAM is that the configuration register has not been set properly.

1. Display the startup configuration:

   show start

   It should display the configuration you saved before the power-off. If you recognize this configuration as the correct one, but it still is not loaded upon startup, the fouled-up configuration register settings are the likely cause.
2. Set configuration register to 0x2102:

   Router#configure terminal 
   Router(config)#config-register 0x2102 
   Router(config)#end
   Router#show version
   Configuration register is 0x2142 (will be 0x2102 at next reload)

3. Type command "reload". If you do not want to replace your existing "startup-config" (configuration file) with something else, do NOT save config.

Links

1. http://www.cisco.com/en/US/products/hw/routers/ps233/products_tech_note09186a00800a65a5.shtml - Router losing its configuration during reboot.
2. http://pages.swcp.com/~jgentry/topo/cisco.htm - Cisco Router Configuration Tutorial.

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