The Illustrated Network- P70:In this chapter, you will learn about the protocol stack used on the global public Internet and how these protocols have been evolving in today’s world. We’ll review some key basic defi nitions and see the network used to illustrate all of the examples in this book, as well as the packet content, the role that hosts and routers play on the network, and how graphic user and command line interfaces (GUI and CLI, respectively) both are used to interact with devices. | CHAPTER MPLS-Based Virtual Private Networks 26 What You Will Learn In this chapter you will learn one type of virtual private network architecture the MPLS-based VPN and in particular a Layer 2 VPN L2VPN . We ll also briefly look at using PPTP over DSL for remote access another type of arrangement that is often considered a VPN. You will learn how an L2VPN can make CE1 and CE2 appear to be connected by a single LAN creating a virtual private LAN service VPLS between them. We ll also configure a complete VPLS based on L2VPNs. In Chapter 17 on Internet Protocol IP switching we introduced the idea of Multiprotocol Label Switching MPLS and configured a static label-switched path LSP . That chapter showed how the LSP could be used for traffic engineering TE to steer transit traffic away from the least-cost hops traversed by local traffic. This chapter builds on those concepts and explores the security provided by one type of Virtual Private Network VPN Protocol the Point-to-Point Tunneling Protocol PPTP and one type of VPN architecture the MPLS-based VPN. This chapter creates an L2VPN supporting VPLS. It does not create what is known as an L3VPN or BGP MPLS IP VPN which is actually more common. There are a few reasons we will describe an L3VPN but not configure it. Many introductions to VPNs start with L2VPNs before moving on the more complex L3VPNs. In addition there is a much more complete book written about BGP MPLS VPNs available MPLS-Enabled Applications 2nd edition by Ina Minei and Julian Lucek Wiley . We urge all interested readers to obtain this book after completing this one. This chapter deals with more general aspects of security and privacy on the Internet as companies individuals and government organizations blend increasingly sensitive traffic onto a single global public network. PPTP allows workers in home offices to access remote corporate resources such as servers and files over a public ISP s unsecure network. MPLS-based VPNs allow ISP to offer private
