DSL

This allows digital data to be transmitted from your computer to the phone company, achieving a much wider bandwidth. The signal is separated (modulated) so that both the computer and the telephone can be used simultaneously without interruption. Typically, the layout of a DSL network can be split into two parts: The customer's premises and the central office (CO). The customer's PC is connected to a DSL modem, which is then connected to the POTS (Plain Old Telephone System). Data and voice are then split as they are transmitted to the CO. Voice goes to the PSTN (Public Switched Telephone Network) and data goes to the DSLAM (DSL Access Multiplexer). Data is then routed to the Carrier Network, the ISP (Internet Service Provider) and on to the Internet. Speeds of DSL can vary greatly depending on the proximity of your home to the central office. Homes in close proximity may be able to receive data rates up to 6.1 megabits per second, enabling continuous transmission of motion, video, audio and 3-D effects. Typically, however, single connections will provide downstream rates of 1.544 Mbps to 512 Kbps and an upstream rate of approximately 128 Kbps. Just as speed rates can vary, the types of DSL available also varies. ADSL (Asymmetric Digital Subscriber Line) is the most familiar and widely available. The term Asymmetrical reflects the fact that the amount of bandwidth dedicated to downstream traffic is not equal to the amount dedicated to upstream traffic. Thus, the design of ADSL is meant to exploit the one-way nature of most multimedia communications on the Internet. The reasoning behind this design is that the amount of data received from Internet applications in downloading is greater than the data normally received when sending. For this reason, downstream data rates range from 512 kbps to around 6 mbps and upstream rates are limited to around 1 mbps. ADSL is usually preferred in small businesses and in residential locations where downstream speeds are more important than upstream speeds.