This section describes the origin and basic concepts of L2TP.
The Layer 2 Tunneling Protocol (L2TP) is a type of technology that supports the tunneling of PPP packets. It applies to remote access scenarios for mobile employees to access intranet resources.
When a mobile user accesses intranet resources over the Internet, PPP is used to apply for an intranet IP address from the headquarters. The headquarters authenticates the identity of the mobile user. However, PPP packets cannot be directly transmitted over the Internet due to the restrictions of PPP. Therefore, L2TP VPN is developed to transmit PPP packets over the Internet. L2TP VPN enables mobile employees to remotely access intranet resources, regardless of whether they access the Internet through traditional dialup or Ethernet.