 XYZ POP = Point of Presence Figure 4-8 The middle-mile connection between rural last-mile providers and a core network interconnection point for transport to the Internet. Internet or to a national or undersea cable. The core switches of large providers are also located at POPs. Independently operated data centers where data is managed for multiple enter- prises are another example of sites that require middle-mile connections. These data centers generate large amounts of traffic for which they require high-speed connec- tions on middle-mile networks to backbone POPs. Large carriers such as Verizon and AT&T in the United States carry the majority of middle-mile traffic. Level 3 Communications is an alternative option in some areas. Level 3 offers to connect these rural areas to POPs using spare capacity in its regional and long-haul networks. In the newer networks of these providers, hubs with Gigabit Ethernet switches are able to add and drop off traffic. Connections to Gigabit Ethernet are less costly than those to older SONET/Dense Wavelength-Division Multiplexing (DWDM) facilities. However, they require costly fiber cabling or wireless infrastruc- ture from the rural provider's first-mile network to the middle-mile network switch. The High Cost of Rural Internet Connectivity High-speed middle-mile connectivity is a major problem in rural and sparsely populated areas, worldwide. Although there are a growing number of fixed-wire- less Internet access options, a majority of providers in these areas offer Internet Middle-Mile Networks access-predominately Digital Subscriber Line (DSL) service-with some providing cable modems (see Chapter 5 for a more in-depth description of DSL service). The high costs of laying fiber or high-speed wireless connections to reach a broadband carrier for transport are passed on to customers and result in high end-user prices for cable TV and Internet access. In addition, the DSL broadband speeds to customers are slower than those in densely populated urban areas; thus, the percenta