L2TP
Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks by encapsulating PPP frames within IP tunnels. It was developed by the IETF as a standard that combines features from the older L2F and PPTP approaches to provide a vendor-neutral method for creating VPN connections over IP networks. The original specification is in RFC 2661, with subsequent documents clarifying interoperability with PPP and tunneling control messages.
Operation is based on establishing a tunnel between two endpoints and then creating one or more PPP
Security and deployment: Because L2TP does not provide encryption or integrity protection by itself, VPN implementations
Variations and status: There is an extended version known as L2TPv3 that broadens the protocol’s use cases,