Cable modem technology offers high-speed broadband access to the Internet and World Wide Web services. Through a system of network connections, a cable data network is capable of connecting users to other users anywhere in the global network. While similar to the traditional (analog) dialup modems, a cable modem is significantly more powerful and capable of delivering data approximately 500 times faster. In addition to the faster data rate, an advantage of cable over telephone Internet access is that it is a continuous connection.
With a cable modem, you can hook up your PC to a local cable TV line
and receive broadband data at about 1.5 megabits per second, which is
equivalent to Digital Subscriber Line (DSL) telephone service. A cable
modem can be integrated with a set-top box that provides your TV set
with channels. In most cases, cable modems are furnished as part of the
cable access service and are neither purchased directly and nor
installed by the subscriber.
In a cable network, data from the network to the user is referred to as downstream, while data sent by the user to the network is referred to as upstream. Data from a user to the broadband network is sent in a flexible and programmable system. The actual bandwidth for Internet service over a cable TV line is up to 27 megabits per second on the download path to the subscriber with about 2.5 megabits per second of bandwidth for interactive responses in the other direction.
The upstream and downstream data rates may be flexibly designed using cable modems to match the subscriber’ broadband needs. For instance, a business service can be programmed to receive and transmit at a higher bandwidth. A residential user, however, may be configured to receive higher bandwidth access to the Internet and still be limited to low bandwidth transmission to the network. The data service offered by a cable modem may be shared by up to sixteen users in a local-area network (LAN) configuration.
All cable modems are attached to a cable TV company coaxial cable line and communicate with a Cable Modem Termination System (CMTS) at the local cable TV company office. All cable modems can receive from and send signals to the CMTS but not directly to other cable modems on the line.
