IOS Configuration Files

If you run through setup mode, you’ll be asked if you want to use the configuration you just created. If you say Yes, then it will copy the configuration running in DRAM (known as the running-config) into NVRAM and name the file startup-config. You can manually save the file from DRAM to NVRAM by using the copy running-config startup-config command (or the shortest copy run start):

CiscoTests#
CiscoTests#copy run start
Destination filename [startup-config]?
Building configuration...
[OK]
CiscoTests#

You can view the files by typing show running-config or show startup-config from privileged mode. The sh run command, which is a shortcut for show running-config, tells us that we are viewing the current configuration.

The sh start command-one of the shortcuts for the show startup-config command- shows us the configuration that will be used the next time the router is reloaded. It also tells us how much NVRAM is being used to store the startup-config file:

CiscoTests#sh start
Using 716 out of 155640 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname CiscoTests
!

You can delete the startup-config file by using the erase startup-config command. I’m using this command each time when I’m starting from scratch with some router and after that reloading it. The final result is – clean as a baby router.

CiscoTests#
CiscoTests#erase start
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]
[OK]
Erase of nvram: complete
CiscoTests#
*Mar 1 00:58:59.639: %SYS-7-NV_BLOCK_INIT: Initialized the geometry of nvram
CiscoTests#
CiscoTests#reload
Proceed with reload? [confirm]

*Mar 1 00:59:19.767: %SYS-5-RELOAD: Reload requested by console. Reload Reason: Reload command.

One of the options that you have for backup the configurations is to copy them via the network on some server. This can be done through TFTP protocol, because Cisco IOS has built-in TFTP client. You need to use copy run tftp command, assuming that you have running tftp external server and this server is accessible from the router (check with ping). You can find more information about running a TFTP server in “Useful” tab menu.
It is possible also to save the different config files into the flash: and after that to read them, using the more command.

Router#
Router#copy run
Router#copy running-config flash:
Destination filename [router-confg]?
Erase flash: before copying? [confirm] NO!
Verifying checksum... OK (0x3674)
633 bytes copied in 1.904 secs (332 bytes/sec)
Router#
Router#more fla
Router#more flash:router-confg
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!

What a nice way to have multiple configurations on a single router. BUT be carefull, in the flash are stored the IOS and some additional files and if you lose them it can be a disaster! So, just don’t erase your flash before copying the conf file.

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