Implementing Cisco MPLS: Volume 1, Version 2.1

Service providers today are faced with many challenges in terms of customer demand, including an ongoing need for value-added services. Conventional IP packet forwarding has several limitations, and more and more service providers realize that something else is needed. Not only must service providers be concerned with protecting their existing infrastructure, but service providers must also find ways to generate new services that are not currently supportable using existing technologies.
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Multiprotocol Label Switching (MPLS) is a high-performance method for forwarding packets through a network. MPLS enables routers at the edge of a network to apply simple labels to packets. This practice allows the edge devices—ATM switches or existing routers in the center of the service provider core—to switch packets according to labels, with minimal lookup overhead. MPLS integrates the performance and traffic management capabilities of data link Layer 2 with the scalability and flexibility of network Layer 3 routing. When used in conjunction with other standard technologies, MPLS allows service providers the ability to support value-added features that are critical for their networks.