What Does a Typical Home DSL Modem Setup Look Like?by Keith Evans
With its low cost and surprisingly fast speeds, Digital Subscriber Line (DSL) has become the access method of choice for millions of Internet subscribers. Connection configurations can vary greatly from one user to the next, but certain components are seemingly omnipresent in DSL networks.
DSL is the broadband Internet solution most commonly offered by local exchange carriers, regional Bell companies and other existing telephone service companies. Because the nature of DSL service allows for high-speed Internet connections to be delivered over the existing copper telephone wires already installed (these wires are the same ones that carry voice conversations), telephone companies are the ideal carriers for this service. For this reason, DSL service is easily identified by the connections on the back of the modem: if the modem is connected to the Internet through what appears to be a standard telephone wire (with a plastic RJ-11 modular connection), the Internet service is almost certainly DSL. This comparison is quite easy to perform, especially when comparing DSL to other typical solutions such as cable (which connects to the modem using a thick coaxial cable) or satellite (which requires a special connection to a satellite receiver outside).
The typical DSL configuration consists of a computer with an Ethernet connection to a router or switch; the router or switch is then connected to the DSL modem which, in turn, connects the home network to the Internet. Although the router or switch is completely optional and, in fact, is bypassed by many single-computer users, these devices provide an extra layer of security between the general public on the Internet and potentially sensitive private data on the user's computer. While the typical DSL setup does consist of one DSL modem connected to the Internet and one router, many users connect multiple computers to the Internet using the connection-sharing capabilities of the router. By splitting the incoming Internet connection and coordinating network traffic, sophisticated users can connect dozens of computers to a single DSL modem through a router. This capability means that, while the typical DSL setup features one modem, one router and one computer, multiple-computer configurations are becoming increasingly common.
Digital Subscriber Line service works by modulating computer data into a sound that can be sent across existing telephone lines. While this configuration may sound reminiscent of older dial-up connections, DSL uses a special higher-frequency modulation that allows it to share a telephone line with a simultaneous voice conversation. This sharing means not only that users can surf the Internet and talk on the telephone at the same time, but that the DSL connection can remain constantly connected to the Internet 24 hours per day, 365 days per year.
DSL service connects directly from the user's modem to a telephone company multiplexer, generally located in the same geographic area. A series of multiplexers are, in turn, connected to a an aggregator which may serve a larger geographic area including, in rural settings, an entire region. The aggregator then connects the aggregated DSL data connections to the telephone company's core high-speed data network and, finally, to the Internet backbone. With each step up the network, devices become increasingly complex with incremental amounts of memory, storage and processing capability. Through this complex arrangement of personal computers, modems, and commercial network devices, a DSL user anywhere in the world can connect to the Internet and, ultimately, to any other user anywhere else in the world.
With little doubt, Digital Subscribe Line service offers a convenient, friendly, and relatively inexpensive way for end users to access the Internet at broadband speeds. Operating at a high frequency across existing telephone lines, a DSL connection to the Internet can remain connected indefinitely (assuming, of course, that the user leaves his computer on and continues to pay the telephone company's bill). Because the persistent DSL connection is always on, it is also constantly exposed to intrusive traffic and inquiries from outside web surfers. Hackers and other unscrupulous network users use special software to detect DSL connections and may attempt to gain unauthorized access to the computers on the other end of the connection, putting sensitive and personal data at risk. Using a router on the home network can not only allow multiple computers in the home to share the DSL connection, but also effectively "hides" the connected machines from the outside world (this is accomplished through a process known as network address translation, or NAT).