DSL. What is it, what do I need and how does it work.

DSL Advantages.

DSL Limitations.

        What is DSL

What does DSL stand for?

Digital Subscriber Line. DSL is a modem technology that transforms ordinary phone lines (also known as "twisted copper pairs") into high-speed digital lines for ultra-fast Internet access. DSL also enables access to corporate networks for telecommuters, as well as exciting new interactive multimedia applications such as multiplayer gaming, video on demand and video catalogs.

What Equipment Do I Need?  

FasTrac768 customers will need a compatable ADSL modem and a computer with an Ethernet (Network) card installed.  The ADSL modem is included in ChicagoNet's setup fee and is yours to keep.

All other FasTrac Packages will need an ADSL Router.  All connected computers must have an ethernet card. The DSL Router is included in ChicagoNet's setup fee and is yours to keep.

Is DSL compatible with a Macintosh?

Yes, as long as the end user has an Ethernet 10BaseT (not coax) interface and TCP/IP software (either MacTCP or OpenTransport, which is included in MacOS 7.x and later). Anybody who has been using a Mac for a dialup Internet account has TCP/IP software. TCP/IP has been a standard part of the system software. TCP/IP software is also available as an add-on for those end users that do not already have it.

What is xDSL?

xDSL is the name which has been coined for the family of digital subscriber line technologies ranging from ADSL to SDSL. The "x" represents a varible that can be replaced with either the "A" standing for ASYNCHRONUS or "S" standing for SYNCHRONUS. 

How does xDSL work?

xDSL modems use digital coding techniques to squeeze up to 99% more capacity out of a phone line without interfering with your regular phone services. That means you could be simultaneously talking on the phone or sending a fax - while surfing the World Wide Web, since the DSL service operates off another separate phone circuit and does NOT need to tie-up your current voice and/or fax line.

Will DSL interrupt existing phone service?

No. DSL works on its own phone line. An end user will never experience slower performance when making phone calls.

What is the controversy between CAP and DMT line codes?

CAP and DMT are two "line codes" or modulation systems currently on the market today for xDSL. The Forum has taken no position on the merits or demerits of either. Each line code has its own case to make. All major xDSL vendors belong to the ADSL Forum and set aside their differences while working together to create system guidelines and market positions. As such, it can be fairly represented that the line code issue will have little bearing on the size, speed, or character of the xDSL market as a whole.

DSL Advantages

What are the main benefits of xDSL?

- Uninterrupted, high-speed Internet access that's always on-line
- Cost-effective solution for residential customers, telecommuters and small businesses
- Data Security that exceeds other technologies

How does xDSL compare to cable modems?

xDSL provides a dedicated service over a single telephone line; cable modems offer a dedicated service over a shared media. While cable modems have greater downstream bandwidth capabilities (up to 30 Mbps), that bandwidth is shared among all users on a line, and will therefore vary, perhaps dramatically, as more users in a neighborhood get online at the same time. Cable modem upstream traffic will in many cases be slower than xDSL, either because the particular cable modem is inherently slower, or becasue of rate reductions caused by contention for upstream bandwidth slots. The big difference between xDSL and cable modems, however, is the number of lines available to each. There are no more than 12 million homes passed today that can support two-way cable modem transmissions, and while the figure also grows steadily, it will not catch up with telephone lines for many years. Additionally, many of the older cable networks are not capable of offering a return channel; consequently, such networks will need significant upgrading before they can offer high bandwidth services.

Are there any per-minute or usage charges associated with DSL?

No. DSL is a dedicated network service that costs the same regardless how often it is used or how much data is transferred. This predictability is one of xDSL's most attractive features.

Does DSL have any security issues like cable modems?

No. DSL is not a shared network service like cable modems, which means that one end-user can not see what's on a neighbor's computer using DSL. The service is a private dedicated connection from the end-user to the network.

DSL Limitations

What determines which level of service is available to the end-user?

DSL is a distance-sensitive telecommunications service: increased distance from the central office (CO) means decreased speeds. The closer one is to the CO, the more bandwidth that can be provided.

What other limitations are associated with DSL?

On the FasTrac 768 product, there is a limitation in that a Dynamic IP assignment is used by "forcing" the IP to change after 10 Minutes of idle time or after a continuous 8 hour session. There is no need to "dial in" again, as there is no dial in process to begin with. The IP is simply changed after exceeding those limitations. Server and LAN applications will not operate on this type of connection.

Can I use a telephone or fax machine on my DSL line?

This feature is coming soon.


Email:  Revised: May 1, 2000

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