Conclusion
L2TP protocol

The original idea behind the L2TP protocol was to transport PPP sessions to endpoints anywhere in the network. Since then, a new use for the protocol has been envisaged, that of transporting other Layer 2 protocols.

To meet this new need, a new version of the L2TP protocol has been standardized by RFC3931 (see reference ): L2TPv3. One of the most important aims of this new version, standardized in March 2005, is to make the protocol independent of PPP and, more generally, independent of any Layer 2 protocol it has to transport. Other differences with RFC 2661 (see reference...