ng capabilities allow providers to support service-level guarantees across the entire network. Thus, it not only meets their needs for scalability and reliability but also provides operational advantages that can further reduce expenditures. The advent of the Internet and the resulting productivity gains spurred by the adoption of new technologies are leading to a demand for increased bandwidth and services. Corporations are demanding customized services at greater bandwidth, and consumers are looking for services such as broadband connectivity and VOD. Carriers have to balance the demands of their target markets with the realities of their business. Traditional technologies (such as ATM and SDH/SONET), while being familiar, simply do not match the vision that carriers have for their networks. They are built on expensive infrastructure that cannot scale without large invest- ments. Moreover, the complex management and multiple handoffs between all these technologies cause significant operating overhead. The market opportunity for Ethernet services is clear and exists today. Numerous early adopters have been successful in deploying these services. Carriers are facing a challenge in how to respond to these market dynamics. VPLS with an Ethernet infrastructure can present an optimal solution for carriers to roll out new services profitably. The ben- efits from reduced capital and operating expenditures add up quickly to improve the bottom line. In addition, the ability to leverage existing networks ensures carri- ers that the investments made in older technologies can be preserved and that more returns can be generated from them. There are, however, potential disadvan- tages associated with the use of Ethernet in MANs and WANs. The biggest concern is the lack of QoS capabilities, leading some industry observers to view Ethernet solutions as one of throwing bandwidth at the problem and therefore a short-term strategy at best. Chapter 9 IP Services VPN Security Security is very important to the proper operation of VPN