Hi
About L2TP :
The Layer 2 Tunnel Protocol (L2TP) is an emerging Internet Engineering Task Force (IETF) standard that combines the best features of two existing tunneling protocols: Cisco's Layer 2 Forwarding (L2F) and Microsoft's Point-to-Point Tunneling Protocol (PPTP).
http://www.cisco.com/en/US/tech/tk827/tk369/tk388/tsd_technology_support_sub-protocol_home.html
About PPTP :
Point to Point Tunneling Protocol (PPTP) is a network protocol that enables the secure transfer of data from a remote client to a private enterprise server by creating a VPN across TCP/IP-based data networks. PPTP supports on-demand, multiprotocol, virtual private networking over public networks, such as the Internet.
http://www.cisco.com/en/US/tech/tk827/tk369/tk529/tsd_technology_support_sub-protocol_home.html
regds
