GRE Setting 
This allows you to create a Generic Routing Encapsulation (GRE) tunnel that can tunnel multiple traffic types. 
 
Connection Name: The connection name for the GRE tunnel. 
Tunnel Name: The tunnel name for the GRE tunnel.  
 
Note: this must start with "gre-". 
 
Interface IP Address: The interface IP address to use with the GRE tunnel. 
Subnet Mask: The interface IP address subnet mask to use with the GRE tunnel. 
Tunnel Remote IP: The remote tunnel IP address to use with the GRE tunnel. 
Max TTL: The maximum Time to Live (TTL) of the GRE tunnel packets. 
 
Click Apply to apply the settings and click Refresh to refresh the page.