See Layer 2 Tunnelling Protocol.
Layer 2 Tunneling Protocol. Developed jointly by Cisco Systems, Inc. and Microsoft Corp., L2TP performs end-to-end encapsulation between client and server.
Layer 2 Tunneling Protocol. A standard Layer 2 tunneling protocol that was developed from earlier protocols, i.e. L2F and PPTP. L2TP is used in VPN. Also see tunnel and VPN.