The command copy tftp: running-config is used to retrieve a configuration file from a TFTP server and

merge it with the current running configuration of a Cisco device. This operation is additive, meaning

it integrates the new configuration commands into the existing running configuration without

removing any pre-existing commands unless explicitly overridden.​

This method is particularly useful when restoring configurations to a replacement device, as it allows

for the seamless integration of necessary settings without disrupting the current operational state.​

In contrast, using copy tftp: startup-config would overwrite the startup configuration file, which could

lead to unintended consequences upon the next device reload. The options load tftp: running-config

and merge tftp: running-config are not valid Cisco IOS commands.​

Reference: Supporting Cisco Devices for Field Technicians (FLDTEC) – Maintenance and RMA

Procedures​Cisco

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