Restoring a Cisco router config using a config file
Solution 1:
You'll miss some things by doing it this way. The best option is to copy the config to a tftp server and restore it from there if necessary
copy running-config tftp:
to restore
configure replace tftp://servername/config
Solution 2:
The correct way to restore a config file from backup is to:
copy tftp://path/to/config startup-config
reload
If you copy into the running-config, you'll actually merge with the running config. You'll pick up some elements that you don't want.
Some newer routers have a command to replace the running-config wholesale with an external config, but the exact command escapes me at the moment.