MPLS defines protocols that create a different paradigm for how routers forward packets. Instead of forwarding packets based on the packets' destination IP address, MPLS defines how routers can forward packets based on an MPLS label. By disassociating the forwarding decision from the destination IP address, MPLS allows forwarding decisions based on other factors, such as traffic engineering, QoS requirements, and the privacy requirements for multiple customers connected to the same MPLS network, while still considering the traditional information learned using routing protocols.
MPLS includes a wide variety of applications, with each application considering one or more of the possible factors that influence the MPLS forwarding decisions. For the purposes of the CCIE Routing and Switching written exam, this book covers two such applications in the first two major sections of this chapter:
- MPLS unicast IP
- MPLS VPNs
This chapter ends with a brief introduction to many of the other MPLS applications. Also, as usual, please take the time to check http://www.ciscopress.com/title/9781587201967 for the latest version of Appendix C, "CCIE Routing and Switching Exam Updates," to find out if you should read further about any of the MPLS topics.