This chapter introduced you to an overview of IPsec, including its components and how it implements a secure connectivity solution. Of all of the VPN implementations, IPsec is probably the most complicated one.
Setting up and troubleshooting an IPsec connection is not necessarily a simple process. Therefore, understanding how IPsec works and the types of connections that are built is important when it comes time to troubleshoot connections that won't come up. Whereas this chapter gives you an overview of the IPsec standard and implementation, other chapters will spend more time on the actual configuration and troubleshooting process, because this is different on a product-by-product basis.
Next up is Chapter 4, "PPTP and L2TP," where I discuss an overview of PPTP and L2TP VPN implementations so that you have an understanding as to which VPN implementation, compared to IPsec, makes more sense for your particular network infrastructure. Following this chapter, Chapter 5 will cover the last type of VPN implementation I'll cover in this book: "SSL VPNs."