SoftEther VPN User Forum

How does the L2TP determine the subnet mask and the gateways for different subnets?

1. About the routes
L2TP is not an ethernet connection and the client does not need to and does not know the gateway IP of the routes, but the packets are forwarded to the correct gateway when using L2TP. The client only knows that a subnet should be routed through the L2TP connection.

2. About the subnet mask
The client can specify a static IP address and it is working, but the client cannot specify the subnet mask(e.g. Windows built-in client).

L2TP uses PPP.
PPP doesn't have subnet.

SoftEther VPN server provide virtual router for L2TP session.
So, the server notice IP address of the virtual router as default gateway.

Then how does Softether VPN server know the gateway IP? Does it obtain from the DHCP?

192.168.30.2 is the tap device.
192.168.30.3 is a virtual layer 3 switch.

>>Then how does Softether VPN server know the gateway IP? Does it obtain from the DHCP?
Yes.