For most of us, the Internet starts at our modem. When your modem dials into your Internet service provider, it connects to a special router called an access concentrator, located at the ISP's Point of Presence , usually located in or near a telephone company facility.
High-speed leased lines connect the POPs to the ISP's main data center. Most ISPs provide free email service for their clients, using email servers located at the ISP's data center.
Each ISP must have a high-speed connection to one of the major Internet backbones. There are very high-speed fiber-optic connections that link major ISP data centers, universities, and government agencies. All the major backbones are interconnected, so that if one fails, the others automatically pick up the traffic.
How Traffic Moves over the Internet A growing number of home users get their Internet access from their local cable TV company using cable modem service. The cable provider acts as its own ISP, and maintains high-speed connection to an Internet backbone.
How Traffic Moves over the Internet Many private businesses are connected to the Internet, often using business-class services from an ISP. These users are typically connected using a medium-speed data circuit leased from the local phone company.
How Traffic Moves over the Internet Some of us just can't live a plugged-in life anymore. Several wireless ISPs provide wireless Internet access using wireless PDA devices such as the Plam Vll.
How Traffic Moves over the Internet The Internet would't be very interesting without content, and most of that content comes from Web servers. ISPs often provide free hosting services for their users, and many business host their own Web sites. But organizations with heavy Web server traffic often outsource their Web services to a dedicated Web-hosting provider. These providers use heavy-duty server PCs connected to very high-speed data connections to provide a very high level of service and reliability.