The Layer 2 Tunneling Protocol (L2TP) provides a standard method for setting up and managing L2TP sessions to tunnel a variety of L2 protocols. One of the reference models supported by L2TP describes the use of an L2TP session to connect two Layer 2 circuits attached to a pair of peering L2TP Access Concentrators (LACs)@ which is a basic form of Layer 2 Virtual Private Network (L2VPN). This document defines the protocol extensions for L2TP to set up different types of L2VPNs in a unified fashion.