DSL Modem Technology Promises High-Speed Internet Access for Some

By John Kemp (kemp@ns.uoregon.edu)

Since DSL is a relatively new technology, many people still have general questions about what it is and what it can do. This article attempts to answer some of those questions and describes some of the DSL options now available locally.

So . . . what is DSL?

DSL stands for "Digital Subscriber Line." In a nutshell, it's a new modem technology for allowing high-speed Internet access to homes and small businesses over existing telephone wires.

The name DSL comes from two terms that together describe the technology: "digital" and "subscriber lines." The first term refers to the fact that DSL data transmission is based on digital encoding (i.e., data is represented as ones and zeroes); while "subscriber lines" is the phone companies' historic term for their customer wiring. The key difference between a DSL modem and a traditional modem is that the DSL modem operates at very high speed and utilizes digital signaling.

Why should you care?

DSL could be of interest to certain individuals or small businesses who have a pressing need for a high-speed connection to the Internet, and who are eligible for the service. DSL's performance can be ten times faster than that of existing V90 or 56K modems--and, depending on the type of service that is purchased, even faster than that. The cost of DSL is typically a fraction of other traditional high-speed wide-area technologies, such as ISDN, T1, or Frame Relay, and DSL service is rapidly becoming available in a number of cities throughout the U.S.

The promise of DSL is to extend high-speed Internet access all the way to the home or small business for a relatively modest price. This can enable activities like telecommuting, videoconferencing, file sharing, web serving, or any other network activity that depends on an "always-on" connection, and a connection that has a bandwidth greater than what has previously been available using traditional dialup technology.

How fast is DSL?

The speeds achieved using DSL depend on a number of factors. Currently, a typical USWest DSL connection has a download rate limit of 640Kbps (kilo-bits-per-second) and an upload limit of 272Kbps. Actual performance will vary depending on the current utilization of the intervening network and the performance of the sending and receiving machines involved in the file transfer. File downloads at rates of 40 to 50 KB/s (kilo-bytes-per-second) are not uncommon. Faster rates can be obtained by purchasing higher levels of service at additional cost.

Who is eligible?

In general, only customers who are within 2-3 miles of a phone company's central office are able to receive the service. DSL is distance-limited, so people in remote areas should not expect to be able to subscribe. The best way to find out if you are within range is to check with the phone company providing the service. Locally, USWest is the only current provider; however, other competitive local exchange carriers may also begin to provide service in the near future. USWest maintains a web site at http://megawot.uswest.com/availability/ that has links for checking service availability and applying for service.

There are other institutions that can deploy DSL technology. In special cases, the University of Oregon's Network Services has utilized DSL to establish connections from nearby off-campus buildings to the campus network. These arrangements are typically only considered when the customer has a direct affiliation with the university and has adequate funding to support the service. And again, because of the use of phone wiring, similar distance limitations still apply. Organizations interested in this kind of application may contact Network Services at 346-4395 or send email to nethelp@ns.uoregon.edu

What is an ISP in terms of DSL service?

There are usually two entities involved in a complete DSL service package: one that provides the DSL circuit, and another that provides Internet services. These entities can be the same company or two different companies. You can purchase your DSL modem and order your DSL line from USWest, and they will direct your traffic either to their own Internet Service Provider, USWest.Net, or to a qualified Internet Service Provider (ISP) of your choosing.

In general, an ISP provides services such as an IP address for your computer and the routing of your traffic to the Internet. ISPs can also provide email accounts and other services, such as web page hosting and news server access. In the simplest case, USWest can act as both your DSL line provider and your ISP. In this case, your phone bill, DSL line charges, and ISP charges would all come from the same company. There are also a number of competing ISPs, such as The Pond and Willamette.Net. A complete list of participating ISPs is provided by USWest at http://www.uswest.com/products/data/dsl/isplist.html

Why would I choose one ISP over another?

While you will generally have only one choice in terms of who is providing your DSL line (USWest), you might have a number of choices when it comes to selecting an ISP. The services offered by each ISP vary widely, so care should be taken when making this choice. You'll need to consider a number of factors, including available bandwidth to the Internet, routing topology, the provisioning of static or dynamic IP addresses, email accounts, disk space for web pages, and domain name registration for business use.

The easiest way to determine which services are offered is to call the ISP and talk to a customer service representative. In any case, it is usually not too difficult to switch to a different ISP or to upgrade to a higher level of service at some later date if you decide that additional services are required.

See "More DSL..." for a discussion of alternative services.

What happens to my phone line?

DSL has adequate capacity to carry telephone voice traffic along with data traffic. The two types of traffic are integrated at the DSL modem, and then later split apart at the phone company's central office. The two channels coexist amicably, and it is never the case that you won't be able to use your phone because someone is using the computer, or vice versa.

In order to protect telephone devices (which operate on lower frequencies) from the higher frequencies of the DSL data channel, small filters must be put inline between the telephone and the DSL modem. Once the filters are in place, the phone operates as usual.

How much does it cost?

Initial setup of a DSL connection will require a DSL modem and the installation of the modem and inline phone filters. Installation is relatively simple, and this charge is usually waived if performed by the customer. The cost of the modem will vary, depending on the availability of promotional discounts. Likewise, initial setup costs can vary from $0 to $450, depending on the type of hardware, method of installation, and availability of promotional discounts.

For example, the Cisco 605 internal modem is sometimes provided at no cost. If you perform your own installation, this can end up being a "no cost" setup. Other typical scenarios might involve purchasing the external modem for either $50, $100, or $300. If the customer chooses on-site installation by a USWest technician, this can add a cost of $150. The monthly charge for DSL line service also may vary. Depending on the bandwidth and the type of service you choose, the cost can be $20, $30, $65, and up per month. For an always-on connection with a download speed of 640Kbps (kilo-bits-per-second) and upload speed of 272Kbps, the $30/month charge is typical.

The monthly charge for ISP service is typically $20 a month for basic service. For higher level services that include static IP addresses or web hosting, expect to pay $35 a month or more. In addition, you will continue to pay standard charges for phone service if your phone line is incorporated into your DSL service.

So the overall monthly cost for DSL service, including ISP, will be on the order of $50 a month for a typical installation. For users who need a faster connection to the Internet and the expanded service capabilities that DSL can provide, these types of charges are not unreasonable.

Megabit-Qualified ISPs

For a current list of megabit-qualified Internet Service Providers in Oregon, see the listing provided by USWest at http://www.uswest.com/products/data/dsl/isplist.html#oregon