L2TP was first proposed in 1999 as an upgrade to both L2F and PPTP. Because L2TP can’t provide strong encryption or authentication, another tunneling protocol called IPsec is used in conjunction with L2TP.
L2TP/IPsec encapsulates data twice, which can slow down the connection. However, the protocol makes this up by providing the encryption/decryption process in the kernel and allowing multi-threading that is not possible in the OpenVPN protocol. This fact, theoretically, makes L2TP together with IPsec faster than OpenVPN and safer than PPTP.
L2TP/IPsec is just as easy and quick to set up as PPTP but is much more secure. Yet, because the L2TP protocol uses UDP port 500, there are chances that the VPN connection will be detected and blocked by some firewalls.