Digi TransPort - Configure GRE Interfaces

Configure GRE interfaces
Digi TransPort User Guide 223
Configure GRE interfaces
Generic Routing Encapsulation (GRE) is a means of transporting IP packets from one device to
another through an unencrypted point-to-point IP tunnel. Multiple tunnels may be configured to
multiple devices. Below the GRE Interfaces sub menu, you will find the individual tunnel
configuration. When configured, a GRE tunnel is created between two devices.
Tunnel parameters
Description
A memorable name for this GRE instance, to make it easier to identify it.
IP address
The IP address of the virtual interface used by the tunnel. This parameter is used in
conjunction with the mask parameter below. This parameter MUST be entered for the tunnel
to work.
Mask
Use this parameter with the IP address parameter to clarify the subnet in use on the virtual
interface. This would normally be a 30 bit mask as this is a point-to-point link
(255.255.255.252).
Source IP Address
The two sub options here allows you to specify a source address either from a specified
interface or by manually assigning an address. If you do not select either option the default
address for the route the packet leaves the router through will be used (please note that if the
interface through which the GRE packets exit does not have NATting turned on then the
default router address will be used-by default this will be the Ethernet 0 address).
Use Interface:
The GRE tunnel source interface, which allows the tunnel end point to be a physical interface
rather than a virtual IP address. This is for using GRE without IPSec. These parameters should
not be used if the source address is used in the parameter below. Select from the drop down
boxes the available interface type and number.