Administering Cisco QoS for IP Networks
Tweak and tune your Cisco routers for best performance with this practical guide.
TABLE OF CONTENTS Administering Cisco QoS for IP Networks
Chapter 12: Multiprotocol Label Switching (MPLS)
Introduction
Multiprotocol Label Switching is designed to forward packets through a network with extremely high performance by adding a label to packets as they enter the network at edge routers. Normally, every router along the packet s path looks at each individual piece of the IP header. However, since MPLS applies a fairly simple label to each packet that includes all of the information needed to route the packet, the overhead created by each router looking through the packet s header is greatly reduced, and the packet forwarding capabilities of each router are enhanced.
This chapter, unlike earlier chapters, both introduces MPLS and shows some configuration examples. Since the basic theory of MPLS is fairly simple, separate chapters are not required to discuss theory and implementation. Relatively speaking, MPLS is a new technology, and there are many enhancements, such as the capability to use RSVP with MPLS to request labels, that are being developed but are not yet fully deployable. This chapter focuses on the current RFCs pertaining to MPLS and does not discuss features that may not make it to full implementation.
Understanding MPLS
MPLS is the standardized version of Cisco Systems Tag Switching technology that integrates the flexibility and scalability of Layer 3 routing with the high performance and traffic-engineering capabilities of Layer 2 switching. MPLS is based on the concept of label swapping, in which packets or cells are assigned short, fixed-length labels that tell high-speed switching nodes how data should be forwarded.
The key to understanding MPLS is...
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