David E. McDysan, MCI Corporation
INTRODUCTION TO IP-BASED VPNs
An IP-based virtual private network (VPN) may provide service at layer 2 or layer 3. The focus of this chapter is on layer 3 VPNs, specifically those using the Internet protocol (IP). RFC 3809 (Nagarajan et al., 2004) covers requirements and aspects that are common to both layer 2 and layer 3 VPNs.
Applications of IP VPNs
The public Internet plays an important role for many enterprises (McDysan, 2000). Users can exchange information with individuals anywhere in the world via e-mail, Web sites, transaction systems, file sharing, and file transfer. Furthermore, the Internet is rapidly growing as a means for commercial enterprises to conduct business and to advertise their goods and services. The Internet can help reduce administrative costs by placing the data entry, verification, and think-time aspects of order entry and service parameter selection in the hands of the end user. This replaces the older, less efficient paradigm of people ...