This chapter provided a technology overview that is the foundation of the rest of this book. It started by looking at network security before providing a brief overview of the AVVID program and the Cisco SAFE security blueprint. It then looked at IPSec and the components that make up this framework. There is quite a lot to IPSec, and quite a few permutations can be used, such as encryption and authentication algorithms. This chapter covered each of these options and finished by looking at the five important steps in how IPSec is implemented in all Cisco devices. The next chapters build on this information and delve more into the configuration aspects of VPNs for the Cisco VPN 3000 Concentrator range of products.