Digi TransPort WR11, User Manual

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Configure network interfaces Configure GRE interfaces
Digi TransPort WR Routers User Guide 225
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 the tunnel uses. Use with the Mask parameter. You must
enter this parameter 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 from a specified interface or by
manually assigning an address. If you do not select either option, the router uses the default
address for the route through which the packet leaves the router. If the interface through which
the GRE packets exit does not have NAT enabled, the router uses the default router address,
which is 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. Do not use these parameters
if the parameter below uses the source address. Select the available interface type and number
from the drop-down boxes.