In prior chapters, the implementation of Layer 3 VPN technologies and deployment scenarios was discussed. VPNs can also be deployed at Layer 2 using various technologies. Tunneling is a technology that allows a network transport protocol to carry information for other protocols within its own packets. For example, IPX data packets can be encapsulated in IP packets for transport across the Internet, and these packets are delivered unmodified to a remote device. The packets can be secured using data encryption, authentication, or integrity functions. In this chapter, the operation and configuration of Layer 2 tunneling protocol version 3 (L2TPv3) will be discussed.