L2TP protocol

Posted on 2002-05-15
Last Modified: 2012-06-27
What is L2TP protocol ?
When do we use , and for what ?
Is it the CISCO proprietary ?
Is it the Protocol for VPN session ??

thanks in advances.
Question by:leumas
  • 3
  • 2

Accepted Solution

cincin77 earned 50 total points
ID: 7013350
L2TP is a tunneling protocol.
It is not Cisco proprietary.
It is a protocol used in one type of the VPNs; layer 2 VPNs.

Let me explain:
When you connect to the internet and connect to a host in the internet, you go through several ISPs so several routers, switches etc. Another way to connect to that machine is a through a modem connection. Your modem calls a modem connected to your target machine.

Tunneling in the internet emulates this modem connection. Although you go through several intermediate machines in order to reach your target machine in the inernet, if you use a layer 2 tunneling protocol like L2TP, you feel like you are directly connected to your target.

L2TP creates a new packet which includes your original packet(so for example if you are part of a network in which private IPs are used, you are connceted to the target with this 'non-routable in the internet' IP address.). As this is a layer 2 tuneling protocol, you are like in that target LAN.


Author Comment

ID: 7013365
So L2TP looks like IPSEC ?? Is that right ?

Expert Comment

ID: 7013371
IPSEC is a tunneling protocol in layer 3.
You cannot carry anything but IP over IPSEC. With L2TP os a nother tunneling protocol in layer 2 you can carry IP, Netbios, IPX ....

Author Comment

ID: 7276505
Thanks so much cincin

Author Comment

ID: 7276533
Thanks sir.

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

New Server  was moved from behind Router R2 f0/1 to behind router R1 int f/01 and has now address But we want users still to be able to connected to it by old IP. How to do it ? We can used destination NAT (DNAT).  In DNAT…
How to set-up an On Demand, IPSec, Site to SIte, VPN from a Draytek Vigor Router to a Cyberoam UTM Appliance. A concise guide to the settings required on both devices
After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

932 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now