Chapter 5. Introduction to MPLS-Based Access VPN Architectures

In this chapter, you learn about the following topics:

• Architecture Overview of MPLS VPN in Broadband Networks

• The Role of the PE and How to Map Subscribers to VRFs

• Introduction to Virtual Home Gateways and Multi-VRF CE

• Detailed Examples of Configuration and Monitoring for Three Different PE Deployment Scenarios: Direct Termination, Two-Box Solution, and Multi-VRF CE

This chapter gets into the central topic of this book: MPLS-VPN architectures for broadband and why they look the way they do. The chapter is divided into roughly two different sections. The first looks at how the different types of broadband traffic are mapped to an MPLS VPN, and the side effects of connecting potentially many hundreds of thousands of subscribers to a PE. There are two main design options: direct termination and two-box solutions. Direct termination is the typical design for bridged access. PPP architectures are more complex, as usual, and can use either. To make things more digestible, this chapter avoids mentioning any features developed specifically for these architectures. The idea is to take what exists and see how far it can go.

In the second section, the chapter moves from the abstract to the concrete and shows Cisco IOS configurations and monitoring commands for Virtual Home Gateways, whether they use direct termination or two-box solutions. A complete solution involves more than is shown in this chapter: The configurations are deliberately simple. Chapter 6, "Wholesale MPLS-VPN Related Service Features," goes into the full details of VRF-aware features, especially regarding how to integrate RADIUS and DHCP into the solution.