Digital Subscriber Line (DSL) is an always on internet connection that is several to dozens of times faster than a 56K modem. There are several different classes of DSL all under the xDSL umbrella (ADSL, ADSL Lite, CDSL, HDSL, SDSL, and VDSL).
Some telecom companies offer what is known as Asymmetrical Digital Subscriber Line (ASDL) which means that the speed of the receiving data is different than the speed of sending data (typically 768 kbps download/128 kbps upload).
With ADSL your telecom company (telco) splits one of your voice phone lines, sending Internet data at high frequencies and allowing you to use the lower frequencies for phone calls. This brings high-bandwidth connectivity over ordinary copper telephone lines. A POTS (Plain Old Telephone Service) splitter, also known as a low-pass/high-pass filter, separates the voice and data portions of the DSL line. Current DSL technology requires two POTS splitters: one in the telco's central office, and one in the customer's premises.
Synchronous Digital Subscriber Line (SDSL) uses a separate telephone line for DSL services.
Your telco will tell you what the system requirements are for your machine. In addition to a capable computer system, you may need a network interface or DSL modem. Your specific provider can answer this as well.
The condition of the inside telephone wiring at your place of residence plays a role in the ability to use DSL.
Most telcos handle the installation of DSL, and let another service provider handle the actual internet services. Note: If you already use America Online as your service provider, they offer a plan called "Bring your own access," which lets you connect to their services using your DSL connection at a reduced rate.
The first and most obvious advantage is speed. A DSL connection is significantly faster than a regular modem connection.
Another advantage is that your connection to the internet is instantaneous and available 24 hours a day.
Most service providers allow you to request or purchase a static IP address (an IP address that never changes). With a static IP address you can run various servers such as your own Web site, FTP site or game server.
With a low-cost router you have the ability to share your internet access between several local machines. Some routers can act as a DHCP server and utilize IP masquerading allowing you to use several different computers with just one IP address.
The first advantage over a cable modem is that cable is an RF network. This means that it is vulnerable to transient problems "within the network" from RF interference.
The second advantage is, that since the cable network bandwidth is split between multiple households, performance suffers during heavy usage periods. Thus DSL is generally faster than a cable modem during peak usage periods.
The third advantage is, that since many cable companies use a very narrow bandwidth for their upstream communications, uploads can be slower than ASDL.
Depending on the service provider, you may need to provide an network interface controller (nic) such as an Ethernet card. Price range for a 10/100mbps auto-sensing PCI network card for a PC is currently from $20-$60. Another connection option is a USB DSL modem. These are newer and more likely to suffer from incompatibilities wth your PC or operating system, but they have the advantage of working on the Macintosh, and possibly USB capable laptops as well.
Since your computer sits directly on the Internet, it is open to attacks from hackers, therefore some sort of firewall software should be used. Many firewall systems are commercially available.
Currently DSL is not available in every area. Subscribers must be within 3 miles of a a DSL-equipped central office or DSL Gateway.
Not all customers within 3 miles of a DSL-equipped central office or DSL Gateway will qualify for DSL service, due to existing conditions of the telephone line. Examples of limiting conditions are bridge taps and load coils, which are used as part of the telephone company infrastructure to provide better voice service. These devices interfere with the DSL signal. When a customer's line has these conditions, the line is not qualified to carry the DSL signal. Historically, approximately 60 - 65% of customers out of each central office will qualify for the service.
Last updated: 11 January 2001
Comments: webmaster
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