40
Enable
Click to enable GRE
Enable
Name
User defines name of GRE tunnel
tun0
Local visual IP
Set local virtual IP
0. 0. 0. 0
Destination Address
Set remote IP address
0. 0. 0. 0
Peer visual IP
Set peer virtual IP
0. 0. 0. 0
Peer Subnet Address
Set peer subnet IP address
0. 0. 0. 0
Peer Subnet Mask
Set remote netmask
255.
255.
255. 0
Key
Configure the key of GRE tunnel
N/A
NAT
Click to enable NAT
Disable
Description
For recording the significance of each GRE
tunnel configuration
N/A
3.6.4 L2TP Client
L2TP, one of VPDN TPs, has expanded the applications of PPP, known as a very important VPN
technology for remote dial-in user to access the network of enterprise headquarters.
L2TP, through dial-up network (PSTN/ISDN), based on negotiation of PPP, and could establish a
tunnel between enterprise branches and enterprise headquarters so that remote user has access
to the network of enterprise headquarters. PPPoE is applicable in L2TP. Through the connection
of Ethernet and Internet, a L2TP tunnel between remote mobile officers and enterprise
headquarters could be established.
L2TP-Layer 2 Tunnel Protocol encapsulates private data from user network at the head of L2 PPP.
No encryption mechanism is available, thus IPSes is required to ensure safety.
Main Purpose: branches in other places and employees on a business trip could access to the
network of enterprise headquarter through a virtual tunnel by public network remotely.
Typical L2TP network diagram is shown below:
