Introduction

This book is based on the following courses from the SRC Program: Alcatel-Lucent's “Border Gateway Protocol,” “Virtual Private Routed Networks,” and “Multicast Protocols.” These courses will help you prepare to take and pass the exams required to achieve the Alcatel-Lucent Service Routing Architect (SRA) certification. This book explains the details of BGP, virtual private routed networks (VPRNs), and multicast, including multicast VPN (MVPN). It is intended for experienced network professionals who have achieved the Network Routing Specialist II (NRS II) certification or have experience with IP/MPLS networking technologies.

Although a primary focus of the book is to help you prepare for the Alcatel-Lucent SRA lab exam, ASRA4A0, the protocols and technologies described are at the core of today's IP/MPLS VPN service networks and thus are useful as a reference even if you are not intending to take the exam.

Upon completing this book, you should be able to:

• Describe the overall structure of the Internet and the purpose of an autonomous system (AS)
• Describe the operation of BGP
• Explain the differences between iBGP and eBGP and the reason for the iBGP full mesh
• Describe how BGP sessions are established and maintained
• Describe the most significant BGP attributes and their meanings in a BGP Update
• Describe the BGP route selection process
• Configure a BGP peering session on the Alcatel-Lucent 7750 SR
• Describe the different BGP address families
• Describe how BGP policies and attributes are used to control the distribution and selection of BGP routes
• Configure BGP policies to influence the advertisement and selection of BGP routes
• Describe the use of confederations and route reflectors to increase the scalability of iBGP deployments
• Configure a network of 7750 SRs with a BGP route reflector
• Describe the purpose of a VPRN and how it is perceived from a customer's perspective
• Describe the key mechanisms and features that make up the VPRN architecture
• Explain the role of the virtual routing and forwarding table in a VPRN
• Describe the operation of the control plane in a VPRN
• Explain how routes and labels are exchanged in a VPRN
• Describe the transmission of customer data in a VPRN
• List the key components required to configure a VPRN
• Describe the loop prevention techniques required in VPRNs
• Configure and verify 7750 SRs for VPRN operation
• Describe the purpose and operation of hub and spoke VPRNs
• Configure a hub and spoke VPRN on the 7750 SR
• Describe the purpose and operation of extranet VPRNs
• Configure an extranet VPRN on the 7750 SR
• Describe the techniques to provide Internet access with VPRNs
• Describe the operation of the three inter-AS VPRN models: model A, model B, and model C
• Configure and verify inter-AS VPRNs on the 7750 SR
• Describe the requirement for carrier supporting carrier (CSC) VPRN
• Describe the exchange of customer routes in a CSC VPRN
• Describe the control and data plane operation in a CSC VPRN
• Configure and verify a CSC VPRN on the 7750 SR
• Explain the purpose of a multicast routing protocol
• Describe the IPv4 and IPv6 multicast address structure
• Describe the operation of the IGMP protocol
• Describe the operation of the MLD protocol
• Describe the operation of the PIM protocol
• Configure and verify a multicast network on the 7750 SR
• Describe the methods used to provide resiliency in a PIM network
• List the requirements for supporting multicast traffic in a VPRN
• Describe the approaches used to implement multicast VPN
• Explain the key concepts and terminology for an MVPN network
• Describe the purpose and operation of the I-PMSI
• Describe the purpose and operation of the S-PMSI
• Describe the MDT-SAFI address family and its use for BGP Auto-Discovery (A-D) in Draft Rosen
• Configure and verify Draft Rosen in a VPRN on the 7750 SR
• Compare the capabilities of Next Generation MVPN (NG MVPN) with Draft Rosen
• Describe the MCAST-VPN address family
• Explain how BGP A-D is used for auto discovery in an NG MVPN
• Describe the use of BGP A-D routes for customer PIM signaling in an NG MVPN
• Configure and verify NG MVPN on the 7750 SR
• Describe the operation of multipoint LDP for signaling point-to-multipoint (P2MP) LSPs
• Describe the operation of multipoint RSVP-TE for signaling P2MP LSPs
• Configure and verify NG MVPN to use P2MP LSPs on the 7750 SR

Besides describing these technologies in detail, the book provides many examples of how they are configured and verified on the Alcatel-Lucent 7750 SR. In addition, most chapters contain practical exercises that help solidify your understanding of the material. Solutions to the exercises, with a detailed explanation of the configuration, are available from the Wiley website at http://www.wiley.com/go/alcatel-lucent-sra.

How This Book Is Organized

The book is divided into three sections, each corresponding to three courses leading to the SRA certification. We assume that you have already completed the NRS II ­certification, or have a comparable level of experience. The three sections of the book are the following:

• Border Gateway Protocol (BGP)—This section corresponds to the Alcatel-Lucent “Border Gateway Protocol” course and helps you prepare for the written exam 4A0-102.
• Virtual Private Routed Networks (VPRNs)—This section corresponds to the Alcatel-Lucent “Virtual Private Routed Networks” course and helps you prepare for the written exam 4A0-106.
• Multicast Routing —This section corresponds to the Alcatel-Lucent “Multicast Protocols” course and helps you prepare for the written exam 4A0-108.

The first section of the book is made up of Chapters 1 through 7 and describes BGP.

Chapter 1 provides an overview of the three major topics covered in the book; BGP, VPRN, and multicast. This is intended as a high-level introduction to the important characteristics and operation of these technologies.

Chapter 2 describes the overall architecture of the Internet and how service ­providers interconnect their networks with BGP.

Chapter 3 describes the basic operation and components of BGP. We describe how a BGP peering session is established and how messages are exchanged between ­neighbors. The difference between iBGP and eBGP sessions and the requirement for a full iBGP mesh is explained. The format of the BGP network layer reachability ­information (NLRI) and the major attributes of a BGP Update and their meanings are also described.

In Chapter 4, we go into the details of BGP configuration and its operation in SR OS. We describe the BGP databases and the BGP route selection process. The ­configuration of groups and BGP peers is shown, as well as the verification of peering sessions. We also introduce the other BGP address families and BGP for IPv6.

Chapter 5 introduces the use of BGP policies to control route selection. BGP ­policies are the primary tool for controlling the distribution of routes and thereby the flow of traffic between service provider networks. The policy capabilities we describe include prefix-lists, AS-Path, communities, aggregate routes, MED, and Local-Pref.

In Chapter 6, we explain the issue of BGP scalability within the service provider network and the techniques applied to enable large-scale deployments. The three main approaches are to divide the network into confederations, deploy route reflectors, and use MPLS shortcuts. Most production networks use at least one or a combination of these techniques.

Chapter 7 describes additional BGP features, mainly to improve resiliency and convergence times. This is especially important when BGP is used to support VPN services. The techniques described in this chapter are BGP Best External, Add-Paths, and fast reroute.

The second section of the book covers virtual private routed networks (VPRNs) and is composed of Chapters 8 through 11.

Chapter 8 introduces the VPRN, starting with the basic components, configuration, and verification. It includes the provider to customer route exchange and the exchange of routes across the provider core, including the details of the route ­distinguisher and route target. Besides the control plane operation, the transport ­tunnel and data plane are also described.

The simplest VPRN topology is a full mesh between all PEs. Chapter 9 covers the issue of loop detection and some more complex VPRN topologies, including hub and spoke, CE hub and spoke, and extranet VPRNs. We also describe three different approaches to configuring a VPRN to provide Internet access.

Deploying a VPRN that spans the network of more than one service provider brings additional complexities; these deployments are known as inter-AS VPRNs. Chapter 10 describes the operation and configuration of the three different types of inter-AS VPRNs supported in SR OS: model A, model B, and model C.

Chapter 11 describes carrier supporting carrier (CSC) VPRN. CSC VPRN is a hierarchical approach to building VPRNs in which a super carrier's...