L2Tp/Pptp - TP-Link SafeStream TL-ER6120 User Manual

and the default gateway of remote peer are 172.30.70.151 and 172.30.70.161 respectively. Security
protocol and other parameters for IPsec tunnel and the remote router should be configured the same.
As Security Association is unidirectional, an ingoing SA and an outgoing SA are created to protect data
flows for each tunnel after IPsec tunnel is successfully established. The ingoing SPI value and
outgoing SPI value are different. However, the Incoming SPI value must match the Outgoing SPI value
at the other end of the tunnel, and vice versa. The connection status on the remote endpoint of this
tunnel is as the following figure shows. The SPI value is obtained via auto-negotiation.

3.5.3 L2TP/PPTP

Layer 2 VPN tunneling protocol consists of L2TP (Layer 2 Tunneling Protocol) and PPTP (Point to
Point Tunneling Protocol).
Both L2TP and PPTP encapsulate packet and add extra header to the packet by using PPP (Point to
Point Protocol). Table depicts the difference between L2TP and PPTP.
Protocol Media
PPTP IP network
IP
UDP, frame relay
L2TP virtual
X.25
circuit
3.5.3.1 L2TP/PPTP Tunnel
On this page, you can configure the L2TP/PPTP VPN.
Choose the menu VPN→L2TP/PPTP→L2TP/PPTP Tunnel to load the following page.
Tunnel
Single tunnel
network of
circuit, Multiple tunnels
virtual
Length of Header
6 bytes at least
4 bytes at least
-96-
Authentication
Not supported
Supported