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VPN and L2TP Tunneling

Dear Experts,

I am trying to esatblish a VPN tunnel between 2 routers.

The first idea that came into mind was GRE which is relatively easy to used.

Customer requested the port number that we will be using but since GRE is over IP it will replace the transport layer so no port.

So I looked around trying to find out what tunnel can be transported over TCP or UDP.

I came across L2TP whcih can be either over UDP or over IP (in L2TPv3)

My questions are the below:

  1. Is my analysis correct?
  2. How can you create L2TP tunnels, it doesn't look as easy as GRE?
  3. Where to choose if L2TP will be over IP directly or over UDP?
  4. Do I need AAA authentication for L2TP protocols? I read something about L2TP Client initiated connection but I can't figure out how to use it.
  5. Does anyone have a configuration for L2TP?
  6. What will exactlty be inside the L2TP tunnel over UDP? will it be [IP] | [UDP] | [L2TP] | [L2 Protocol such as Ethernet] | [IP] [the tunneled data]?
  7. Does anyone have a pcap trace for L2TPv2 that can help me understand more?

Your help is much appreciated.

Thank you.

  • LAN Switching and Routing