1.1 HISTORICAL PERSPECTIVE
In only a few years, Multi-Protocol Label Switching (MPLS) has evolved from an exotic technology to a mainstream tool used by service providers to create revenue-generating services. There is rapid deployment of MPLS-enabled services and active development of new mechanisms and applications for MPLS in the standards bodies. This book aims to describe the fundamental mechanisms used by MPLS and the main service types that MPLS enables, such as Virtual Private Networks (VPNs). We include descriptions of new applications of MPLS that are currently under development.
The history of MPLS and its precursors is described in [Davie Rekhter] and [Doyle Kolon]. The first Internet Engineering Task Force (IETF) MPLS Working Group Meeting took place in April 1997. That working group still exists, and MPLS has grown to the extent that it underpins much of the activity of several other working groups in the IETF, such as Layer 3 VPN (l3vpn), Layer 2 VPN (l2vpn), Pseudo Wire Emulation Edge-to-Edge (pwe3) and Common Control and Measurement Plane (ccamp). Part of the original MPLS problem statement [MPLS97] from the first MPLS working group meeting is shown below. It contains four items that the group aimed to address through the development of MPLS. It is interesting to examine these to see which items are still relevant today:
1. Scalability of network layer routing. Using labels as a means to aggregate forwarding information, while working in the presence ...