MPLS-Enabled Applications: Emerging Developments and New Technologies

3.1. INTRODUCTION

In the Traffic Engineering chapter (Chapter 2) we have seen how MPLS traffic engineering allows operators to carry traffic with stringent QoS guarantees such as voice and video. However, these applications require high-quality service, not just when the network is in a normal operating condition but also following a failure. Voice and video are referred to as 'fragile traffic' because they are real-time in nature and therefore cannot recover from traffic loss using retransmissions. Therefore, protection and restoration mechanisms are necessary to handle the failure case quickly. The ability to provide such fast protection is essential for converging voice, video and data on to a single MPLS network infrastructure.

This chapter deals with protection and restoration in MPLS networks. We will start by discussing the use of bidirectional forwarding detection (BFD) for fast-failure detection. Then we will take a look at path protection and at fast reroute using local protection and will see why MPLS-TE has become a synonym for fast reroute in MPLS networks. Finally, we will look at work currently in progress for protecting MPLS traffic that is not forwarded along a TE path, such as LDP traffic. This chapter assumes familiarity with RSVP and with basic TE concepts.