What is Running Configuration?
The term running configuration refers to the router or switch configuration that is currently active and running. The running configuration is stored in memory (RAM) and is loaded each time the router or switch starts up. Changes that are made to the running configuration take effect immediately, without requiring a reboot of the device.
The running configuration can be thought of as the “live” or “active” configuration, as it represents the router or switch’s current configuration.
What is Startup Configuration?
The startup configuration is the configuration that is loaded each time the router or switch starts up. It is typically stored in non-volatile memory (NVRAM), although it can also be stored in other types of memory, such as a TFTP server.
The startup configuration includes all of the settings that are required for the router or switch to function, such as passwords, interface settings, routing information, and so on.
Unlike the running configuration, changes made to the startup configuration are not applied until the router or switch is rebooted. For this reason, it is important to ensure that the startup configuration is saved (backed up) regularly, in case the device needs to be rebooted for any reason.
When a router or switch is first booted up, it will check for a valid startup configuration. If one is not found, the device will enter setup mode, which allows the administrator to manually configure the basic settings required for the device to function.
Once the initial setup is complete, the administrator can save the running configuration to the startup configuration, so that the settings will be preserved across reboots.
Why is Running Configuration Important?
The running configuration is important because it represents the router or switch’s current state. Any changes that are made to the running configuration take effect immediately, which can be useful when troubleshooting or making small changes.
However, it is important to remember that changes made to the running configuration are not saved across reboots, so they will be lost if the device is restarted. For this reason, it is generally a good idea to make changes to the startup configuration instead, so that they will be preserved.
Why is Startup Configuration Important?
The startup configuration is important because it is used to configure the router or switch each time it starts up. This can be useful if the device needs to be rebooted for any reason, as the configuration will be reloaded from the startup configuration file and all of the settings will be restored.
It is also important to remember that changes made to the startup configuration are not applied until the device is rebooted, so it is important to save (or backup) the startup configuration regularly.
Running and Startup Configuration Commands
startup-config: This command is used to boot the router using a saved configuration file. The contents of NVRAM are copied into RAM, and the router boots using the startup configuration in RAM.
running-config: This command is used to view or change the running configuration of the router. The running configuration is stored in RAM and is used to configure the router.
reload: This command reboots the router.
write memory: This command copies the running configuration from RAM to NVRAM.
copy running-config startup-config: This command copies the running configuration from RAM to NVRAM.
show startup-config: This command displays the contents of the startup configuration file.
show running-config: This command displays the contents of the running configuration file.