Chapter 1. MPLS Overview

Multiprotocol Label Switching (MPLS) has evolved from being a buzzword in the networking industry to a widely deployed technology in service provider (SP) networks. In recent years, MPLS has also been adopted by the enterprise and federal market segments. MPLS is a contemporary solution to address a multitude of problems faced by present-day networks: speed, scalability, quality of service (QoS) management, and traffic engineering. Service providers are realizing larger revenues by the implementation of service models based on the flexibility and value adds provided by MPLS solutions. MPLS also provides an elegant solution to satisfy the bandwidth management and service requirements for next-generation IP–based backbone networks.

This chapter introduces you to the following basic MPLS concepts:

• Unicast IP forwarding in traditional IP networks

• Architectural blocks of MPLS

• MPLS terminology

• CEF, FIB, LFIB, and LIB

• MPLS label assignment

• MPLS LDP session establishment

• MPLS label distribution and retention

• Penultimate hop popping

• Frame-mode MPLS operation and loop prevention

• Cell-mode MPLS operation, VC-merge, cell interleaving, and loop prevention