D-Link DFL-200 manual Introduction to Pptp, Introduction to L2TP, Point-to-Point Protocol

Introduction to PPTP

PPTP, Point-to-Point Tunneling Protocol, is used to provide IP security at the network layer.

A PPTP based VPN is made up by these parts:

•Point-to-Point Protocol (PPP)

•Authentication Protocols (PAP, CHAP, MS-CHAP v1, MS-CHAP v2)

•Microsoft Point-To-Point Encryption (MPPE)

•Generic Routing Encapsulation (GRE)

PPTP uses TCP port 1723 for it's control connection and uses GRE (IP protocol 47) for the PPP data. PPTP supports data encryption by using MPPE.

Introduction to L2TP

L2TP, Layer 2 Tunneling Protocol, is used to provide IP security at the network layer.

An L2TP based VPN is made up by these parts:

•Point-to-Point Protocol (PPP)

•Authentication Protocols (PAP, CHAP, MS-CHAP v1, MS-CHAP v2)

•Microsoft Point-To-Point Encryption (MPPE)

L2TP uses UDP to transport the PPP data, this is often encapsulated in IPSec for encryption instead of using MPPE.

Point-to-Point Protocol

PPP(Point-to-Point Protocol) is a standard for transporting datagram’s over point-to-point links. It is used to encapsulate IP packets for transport between two peers.

PPPconsists of these three components:

•Link Control Protocols (LCP), to negotiate parameters, test and establish the link.

•Network Control Protocol (NCP), to establish and negotiate different network layer protocols (DFL-200 only supports IP)

•Data encapsulation, to encapsulate datagram’s over the link.

To establish a PPP tunnel, both sides send LCP frames to negotiate parameters and test the data link. If authentication is used, at least one of the peers has to authenticate itself before the network layer protocol parameters can be negotiated using NCP. During the LCP and NCP negotiation optional parameters such as encryption, can be negotiated. When LCP and NCP negotiation is done, IP datagram’s can be sent over the link.