Digi TransPort WR31 User Manual page 456

Configure Virtual Private Networking (VPN)
L2TP n parameters
Act as a listener only
When enabled, the router does not actively attempt to establish an L2TP tunnel. In this mode, it
will only use L2TP if the remote host requests it. When unchecked, the router will actively try to
establish an L2TP connection with the remote host.
Enable Server mode
When enabled, the router acts as an L2TP server.
Initiate connections to a.b.c.d
The IP address of the remote host, such as the device that will terminate the L2TP connection.
Use a.b.c.d as a backup
It is possible to specify a backup remote L2TP host server using this parameter. The text box
contains the IP address of the remote server to use.
Bring this tunnel up All the time/On demand
This parameter only applies to tunnels initiated from this router.
Bring this tunnel down if it is idle for h hrs, m mins, s secs
These radio buttons select whether or not the tunnel is permanently available or not. When set
to On demand, the tunnel will not activate automatically but will wait until it is triggered by PPP.
When set to On demand the values in the text boxes determine the timeout after which the L2TP
tunnel will closed down after the last L2TP call on that tunnel.
L2TP Window Size
The L2TP window size is selected from this drop down list. Available values are from 1 to 7.
Route UDP packets over interface x,y
These two text boxes specify the interface and its instance number for L2TP UDP sockets.
Specifying these parameters allow the router to raise the interface should it be disconnected.
Digi TransPort WR Routers User Guide
IPsec parameters
456