L2TPbased

L2TPbased is a term used to describe systems, configurations, or deployments that rely on the Layer 2 Tunneling Protocol (L2TP) to carry traffic across an IP network. L2TP encapsulates PPP frames or other layer 2 payloads so they can be transmitted over an IP network, enabling virtual private networks and network extension across the internet or wide area networks.

Because L2TP provides tunneling but not strong encryption on its own, most L2TPbased deployments use L2TP in combination with IPsec for security, commonly known as L2TP/IPsec. This combination provides confidentiality, authentication, and integrity protection for traffic traversing the tunnel. L2TP/IPsec can be used for remote access VPNs and site-to-site VPNs, supporting various user authentication methods and encryption settings.

In addition to the standard L2TP tunnel, L2TPv3 is a later variant that supports layer 2 tunneling between peers. L2TPv3 is designed for extending a broadcast domain across IP networks and can carry Ethernet-like traffic, enabling network bridging or remote LAN extension.

Operationally, an L2TPbased deployment involves tunnel endpoints, often called LACs (L2TP Access Concentrators) and LNSs (L2TP Network Servers) in older terminology, or simply L2TP peers. A control channel negotiates the tunnel, while payload traffic, such as PPP frames or VLAN frames, is encapsulated and transported over UDP-based tunnels set up between endpoints. NAT traversal (NAT-T) is commonly supported to work behind firewalls.

Security considerations include ensuring proper IPsec configuration, strong authentication, and protection against common VPN threats. L2TP by itself provides no encryption, so deployment typically relies on IPsec or alternative encryption options. Compatibility with client devices and consistency of encryption and authentication settings are important for reliability.