The use of GRE tunnels cannot be overemphasized, giving you the ability to perform dynamic routing over the vpn tunnel interface and also allow multicast traffic. In this configuration, we will configure a GRE tunnel and make sure that there is a route for the destination subnet that will make use of the GRE-Tunnel.
Complete configuration scenario - see attached
Annotate your configuration with comments where needed. - see attached
1. Verify the GR interfaces are up.
user@router# run show interfaces terse |match gr
2 Verify tunnel destinations are in local route table:
user@router# run show route 10.1.1.2
3. Verify the route for the destination network that is reachable through the gre-tunnel: