How To Understand The History Of Mpls

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1 CHAPTER Introduction 1 Multiprotocol Label Switching (MPLS) is over 10 years old. Born at a time when the Internet had just become a household word, MPLS had a hugely enthusiastic childhood and rapidly became one of the hottest buzzwords in the networking industry. Deployment, however, followed much more cautiously, and it was some years before MPLS saw wide rollout to carry live traffic in real operators networks. MPLS can certainly now be said to be a mature technology with extensive deployments around the world, and with new applications and enhancements being invented all the time. Unlike some of its precursors (such as ATM and Frame Relay), MPLS deployments have seen extensive use of the control plane right from the very start. In part, that can be attributed to the fact that MPLS leveraged many already-mature control plane protocols from the TCP/IP suite of protocols, notably the routing protocols BGP, OSPF, and IS-IS. At times, it seemed that MPLS might suffer from a surplus of control plane protocols when the Constraint-based Routed Label Distribution Protocol (CR-LDP) and Traffic Engineering extensions to the Resource Reservation Protocol (RSVP-TE) were both fighting for the same role as members of the MPLS control plane to support constraint-based routing. Plenty of books have been written to describe how MPLS works and to explain the signaling and routing protocols used in MPLS systems. It is not the objective of this book to revisit that ground, so Chapters 2 and 3 provide only a summary and overview of the basics of the MPLS data plane and control plane. Readers who want to know more about the background and fundamentals of MPLS could do worse than refer to MPLS Technology and Applications by Davie and Rekhter, while The Internet and Its Protocols by Farrel provides a detailed description of all the relevant protocols. The main objective of this book is to introduce some of the newer developments in MPLS. These extensions to the protocols enable new applications and services the next steps in MPLS. As a technology, MPLS is maturing beyond its roots as a useful forwarding mechanism to an advanced and highly functional technology that enables service providers to activate new sources of revenue and new network features for their customers. It is this ability to support new features 1

2 2 CHAPTER 1 Introduction and services that has ensured MPLS s success in the field, much more than any initial aspirations to provide higher speed or lower cost packet forwarding. MPLS started out as a packet technology, but its core aspects forwarding traffic based on some label associated with the traffic have turned out to be applicable to other network technologies. Starting with lambda switching in WDM networks and rapidly extending to cover TDM and layer 2 technologies, the concept of label switching was generalized to produce Generalized MPLS (GMPLS). GMPLS placed new demands on the control protocols and resulted in a set of extensions to the MPLS protocols, but the very nature of GMPLS is that the solutions are generic, and so the GMPLS features have been fed back into the packet networks, and in many cases it is precisely these new protocol extensions that enable the advanced MPLS applications. 1.1 SOURCE MATERIAL Of course, many of the topics covered in this book have already been described at length in other books. In fact, the Morgan Kaufmann Series in Networking includes a comprehensive range of titles that deal with many aspects of MPLS networking. However, each book in the series has as its main focus a particular function or technology, and only some of the chapters or sections are specifically relevant to MPLS. Therefore, what we have done in this book is to bring together material from a number of sources to give you a thorough grounding in the new developments in MPLS. Where necessary, we have edited the source material or written new text to describe the latest technologies. Where the sections of the previous work provide adequate description, we have simply reproduced it here. This results in a single reference that introduces MPLS, explains the basics, describes the control protocols, and discusses advanced topics applicable to MPLS. Readers wanting to know more about a particular topic are encouraged to go to the sources and read more widely. In producing this book, we have drawn on material from the following Morgan Kaufmann books. MPLS Technology and Applications by Davie and Rekhter Written by two experts who personally authored key parts of the MPLS standards, this book has been regarded for many years as the foundation text for all network operators and designers who are interested in MPLS. It has provided a definitive reference for engineers who are implementing MPLS-based products. The Internet and It Protocols: A Comparative Approach by Farrel This book covers all the common protocols and shows how they combine to create the Internet in its totality. Each protocol, including the various MPLS and GMPLS protocols, is described completely, with an examination of the requirements that the protocol addresses and the exact means by which it does its job.

3 1.1 Source Material 3 GMPLS: Architecture and Applications by Farrel and Bryskin The relatively new area of GMPLS is not covered in detail by many books, and this one, written by two leading engineers who have been involved in the design of the GMPLS protocols from the very start, presents a deep and broad view of GMPLS from the protocol essentials, through the early deployment functions, to advanced and future topics. Deploying IP and MPLS QoS for Multiservice Networks: Theory & Practice by Evans and Filsfils In this book, the authors have provided a comprehensive treatise on the subject of Quality of Service (QoS) in IP and MPLS networks. They have included topics such as traffic engineering, capacity planning, and admission control. This book provides real-world case studies of QoS in multiservice networks to help remove the mystery behind QoS by illustrating the how, what, and why of implementing QoS within networks. Traffic Engineering and QoS Optimization of Integrated Voice & Data Networks by Ash In over 35 years of industry research and leadership, Gerald Ash was involved in many projects that advanced the cause of network routing, planning, and optimization. In this book he provides an analysis of the latest thinking about methods for providing traffic engineering and quality of service optimization for integrated voice/data dynamic routing networks. Network Recovery: Protection and Restoration of Optical, SONET-SDH, IP, and MPLS by Vasseur, Pickavet, and Demeester Network Recovery is the first book to provide detailed information on protecting and restoring communications networks. It describes techniques that work at each layer of the networking hierarchy, including optical, SONET/SDH, IP, and MPLS, and it shows how multilayer networks can be constructed to leverage mechanisms that exist in the different layers. MPLS Network Management by Nadeau Practical information on managing MPLS networks remains scarce, but this book, written by the coauthor of most of the MPLS management standards, provides a comprehensive view of the relevant techniques and tools. Developing IP-Based Services by Morrow and Vijayanada This book meets the challenge of uniting business and technical perspectives to provide a cohesive view of the MPLS development and deployment process to enable networking organizations to leverage MPLS to drive traffic and boost revenue.

4 4 CHAPTER 1 Introduction 1.2 CONTENTS OF THIS BOOK This book has 14 chapters following on from this introduction, and these are divided into four sections. Section A provides a refresher of MPLS Basics. Section B describes Advanced Techniques for providing high function services over an MPLS network. Section C examines the key features of Operations, Management, and Security that are necessary for a protocol to move from an experimental concept to a real technology that can be deployed and widely used. Section D looks at some of the techniques used to provide services to customers based on MPLS networks. Chapter 2 provides a refresher and overview of the MPLS data plane. It describes how MPLS applies labels to packets and how labeled packets are forwarded through the network. Chapter 3 gives a summary and reminder about the core MPLS control protocols with special reference to the Label Distribution Protocol (LDP) and RSVP-TE. The fourth chapter introduces GMPLS and explains how the evolution from MPLS to GMPLS took place. It describes some of the new features brought in by the extensions to the MPLS protocols. Chapter 5 discusses Traffic Engineering, one of the key aspects of MPLS that enables the provision of quality of service and allows an operator to manage the network for optimum performance and capacity. Chapter 6 goes into the subject of quality of service in much more detail. When everything else has been described, the customer is usually not particularly interested in the networking technology that the operator uses to deliver services. What the customer really cares about is the quality of the service that is delivered, and this chapter looks at the techniques and mechanisms that are used in MPLS networks to ensure that the network meets the needs and expectations of the end customer. Chapter 7 and Chapter 8 investigate the requirement for restoration and recovery techniques in MPLS networks. They look at how rapidly repairing end-to-end connectivity is an essential component in meeting the users quality expectations, and they explore the techniques enabled by MPLS and GMPLS to achieve recovery through protection or restoration of the forwarding plane. The ninth chapter begins the section on Operations, Management, and Security by describing the Management Information Base (MIB) definitions and tables that enable a consistent and standardized approach to managing MPLS networks, their protocols, and the equipment from which they are constructed. Chapter 10 develops the management theme through an introduction to the monitoring and maintenance protocols that have been developed to check connectivity in MPLS networks, diagnose and isolate faults, and monitor data transfer through the networks.

5 1.2 Contents of this Book 5 Chapter 11 provides an overview of the importance of Security within MPLS. It describes how this function is relevant to clients of MPLS networks as well as within the networks themselves, and it provides an overview of the techniques applied to keep the networks and the data that traverse them safe. The final section of the book begins with Chapter 12 on Virtual Private Networks (VPNs). VPNs have become one of the largest sources of revenue for Internet Service Providers and played a central role in the successful adoption of MPLS. VPNs offer a highly valuable service to customers that allows them to connect disparate sites (offices) and individual computers (such as home workers) to form one seamless network as though it was cabled using private network resources. MPLS offers a simple way for network operators to provide VPNs over a public network that shares resources and capacity with other VPNs and other applications, with relatively straightforward configuration and management. Chapter 13 discusses MPLS pseudowires, another rapidly growing application of MPLS. An MPLS pseudowire is a way to provide emulated connectivity of some non-mpls technology (such as TDM or Ethernet) across an MPLS network. As a service, pseudowires are critical for linking together isolated islands of some legacy or future technology to produce an integrated network, making them fundamental to many migration and installation plans. Chapter 14 examines how MPLS techniques are applied to multidomain networks. Until recently, MPLS was applied only within a single network domain (for example, a routing area or an Autonomous System), with connectivity between MPLS domains being provided at a higher layer, such as by IP routing. But the increasing popularity of MPLS means that it makes sense to consider how the technology can be applied in multidomain networks to provide end-to-end MPLS services. The final chapter, Chapter 15, is devoted to an introduction to multicast and point-to-multipoint MPLS. Multipoint services are gaining significant attention in the Internet with advances in technologies such as IPTV. It is becoming increasingly important to satisfy these services in a network-efficient way using MPLS, and this chapter looks at recent developments in the MPLS protocols to enable point-to-multipoint forwarding in the MPLS data plane. We hope that this selection of material from some of the leading books on the associated topics will combine with the new chapters that we have written to give an up-to-date picture of MPLS and its applications in a rapidly evolving arena.