Multi-Protocol Label Switching (MPLS) is a technology which plays an important role in the next generation networks by providing Quality of Service (QoS) and traffic engineering (TE). This book explains the state-of-art of MPLS architecture, functionality and traffic engineering. It provides the computer simulation and results of voice and video applications over IP and MPLS networks. Different configuration were used to study the performance of MPLS for multimedia applications and compare it with ATM and IP networks.It also introduces MPLS VPNs and the scalability issues in BGP MPLS VPNs. Moreover computer simulation is used to study the failure recovery methods in MPLS networks.