Much has been written about MPLS as a technology and service enablerand certainly, for the past several years, both service providers and enterprises have been deploying MPLS in their networks. This book focuses on the security aspects of MPLS VPNs for implementation, and it goes further to discuss not only MPLS architectural security, but security overall and its impact on deployment. Security, when implemented correctly, enables networks to run business-critical applications, even on a shared infrastructure or on the Internet. Therefore, we have written this book in order to provide best practice guidelines and to discuss security principles as companies deploy MPLS in their networks. Bear in mind that any network, whether it is a voice, Frame Relay, or ATM network, can be attacked and has been. Having an awareness of security and the security requirements for networks and services is the first step toward mitigating against such attacks.