This chapter introduced the fundamentals of MPLS VPN networks and the specific nomenclature used in these environments. You now understand the key security concepts for analyzing MPLS network scenarios?for example the fact that a secure solution consists of the basic components of architecture, implementation, and operation, and that all of those need to be secure in order for an overall solution to be secure. You have seen various types of VPNs, with an emphasis on the security implications of their specific characteristics. At the end of the chapter, you were introduced to a security model that you can reference in later chapters.
A very important concept for security considerations is the zone of trust, which was also introduced here. This concept makes analysis of security architectures easier by defining clear boundaries where security needs to be checked.