Save a large configuration file on a Cisco Router

When a vro configuration is larger than NVRAM, we recommend that you save the configuration on an external TFTP server, and then use the command boot network or boot host on the vro to retrieve the configuration file.
Here we will introduce a method to avoid using external hosts:
1. Configure the vro. In the configuration, configure two commands to call the configuration from the network:
Service config
Boot network tftp: // 10.10.10.10/host-config
Boot host tftp: // 10.10.10.10/startup-config
10.10.10.10 is the IP address of the router LAN port.

2. Add the following two alias commands in the configuration, so that the vro feels that the configuration is downloaded from the external server on the network. In fact, the configuration is still downloaded from the local flash:
Tftp-server flash:/startup-config alias startup-config
Tftp-server flash:/host-config alias host-config

3. Save the Configuration

4. Upload the configuration file to flash

After the configuration is complete, the router restarts. You can read the configuration from the local TFTP server. If you want to save the running configuration:
Copy running-config flash: startup-config