Content IP Services Network IPTV Services Manager Edge Servers Broadcast Server VOD Server Content Distribution Server IPTV Services IPTV Client IPTV Client TV + Set-top Box PC + Set-top Box Cable Figure 9.8 The IPTV architecture VPNs are a crucial requirement for businesses because they distribute mission- critical and sensitive traffic to remote locations. More and more often, customers are looking at mechanisms for securing traffic and for extending the reach of the enterprise to geographically dispersed locations. VPN technology is also being extended to the home office, providing telecommuters with networking security and performance comparable with that available at the office. A big driver of interest in VPNs has been that customers need to communicate with people outside their enterprise, not just those inside the enterprise. As men- tioned in Chapter 5, "Data Communications Basics," in the 1980s, about 80% of Chapter 9 IP Services the information that was used within a given address of a business came from within that address. Only 20% was exchanged outside the walls of that location. Today, the relationship has reversed: As much as 80% of information exchanged is with points outside a given business address. Another reason for interest in VPNs has been that customers want to quickly and securely change their access points as changes occur in their businesses. Many strategic alliances and partnerships require companies to exchange messages quickly. Some of these are temporary assignments-for example, a contractor building a fiber-optic loop or an applications developer building a new billing system-that might last a few months, during which time the individuals involved need to be incorporated into the network. Leased lines are infamous for requiring long waits for provisioning-often 6 to 18 months. VPNs allow rapid provisioning of capacity where and when needed. Traffic has steadily migrated away from traditional networks based on leased lines (see Figure 9.9) to public networks. As a result, we're seei