Layer 2 VPN Architectures introduces readers to Layer 2 Virtual Private Network (VPN) concepts, and describes Layer 2 VPN techniques via introductory case studies and comprehensive design scenarios. This book assists readers looking to meet those requirements by explaining the history and implementation details of the two technologies available from the Cisco Unified VPN suite: Any Transport over MPLS (ATOM) for MPLS-based cores and Layer 2 Tunneling Protocol version 3 (L2TPv3) for native IP cores. The structure of this book is focused on first introducing the reader to Layer 2 VPN benefits and implementation requirements and comparing them to those of Layer 3 based VPNs, such as MPLS, then progressively covering each currently available solution in greater detail.