Cable or DSL: Which Is for You?

by Charlie Schick

As the internet continues to be an integral part of all types of business, the need for reliable high-speed data services has increased. To take full advantage of the internet and its applications, an "always on" high-speed data connection makes a lot of sense. Up to now, the major technologies available for high-speed data access were T1, fractional T1, frame-relay, and ISDN—each with its own particular speed of data transmission, and each with its own high price.

Broadband cable and digital subscriber line (DSL) are two of the newest technologies that have emerged as the best choices for low-cost high-speed internet access. This article provides a general description of both of them, and is intended to help you decide which is best for you and your business.

Cable broadband
Over the past few years, cable companies have been upgrading their 1-way (to the house) TV network to accommodate high-speed 2-way transmission of information (video or data). On the one hand, this allows cable companies to offer interactive television services, such as digital TV and radio. On the other hand, it lets them offer high-speed internet access.

On a cable network, gaining high-speed access to the internet requires a cable modem, typically at a cost of about $250. On one end, it connects to a computer or a Local Area Network (LAN) via an Ethernet jack. On the other, it connects to the cable TV system network via coax cable.

Installation usually involves a single visit by the cable company to configure your computer or network and to convert your cable video system to a cable video and data system.

Cable Pros
Cable broadband technology has a high theoretical bandwidth of 30 Mbps—more than 500 times faster than that of a basic 56 Kbps modem. In real-world use, cable systems provide throughputs of approximately 500 Kbps downstream (into the computer) and 128 Kbps upstream, which is at least 10 times faster than a 56 Kbps modem. For an average price of $40 per month, this is a good deal.

The 3 largest service providers in the U.S. are AT&T Comcast, Time Warner Cable, and Cox Communications. Call your local cable company and ask if they have broadband service. By now, the companies that do have broadband cable have been heavily promoting the service, so it would be hard to miss.1

Cable Cons
Don't expect to be able to choose from different service providers, especially if you live somewhere other than a large metropolitan area. Due to regulation, most towns have only one cable service provider. If your town or city doesn't have broadband service, you're out of luck.

Another thing to keep in mind is that, although the cable company networks are supposed to conform to a global standard, it is likely that a cable modem purchased for one cable network will not work on another.

Also, the cable network is designed as a large, shared network. Subscribers who are geographically close to each other usually share part of the high-speed cable network.

This means, much like it is with a business LAN, all the computers on the local cable network can see each other and share files, unless the user takes the appropriate security steps (i.e., establishes a firewall or turns off file sharing). Furthermore, within this network, bandwidth is also shared—a single user can make the system drop in speed during a large download. Fortunately, the service providers are aware of this and are actively managing bandwidth, so this should not be a serious issue.

One more issue for businesses is that most cable systems are connected to residences and most cable modem services are designed for the residential market (cable networks were initially deployed for homes). The residential market has different price points, service expectations, and network needs than the typical business.

Cable Pricing
Current prices hover at about $40 per month. There is usually an installation charge and a charge for the cable modem, as well. Also, for additional fees, you can get cable TV service and, sometimes, telephone service. In this case, one connection could serve all your telecommunications needs.

DSL sends high-speed data over existing copper telephone lines. To upgrade a voice-only phone system, line splitters to split voice and data must be installed in both the customer's premises and at the local switching office. There is also a special DSL modem that connects the computer to the phone lines.

Installation usually involves multiple visits so that the phone company, DSL provider, and ISP can test the lines, install the equipment, and activate the line.

DSL Pros
Two common flavors of DSL are asymmetric DSL (ADSL), in which the upstream (away from the computer) speed is slower than the downstream speed, and symmetric DSL (SDSL), in which the upstream and downstream speeds are the same. Some providers offer speeds of up to 7.1 Mbps, but most offer a maximum of 1.5 Mbps upstream and downstream. Pricing for DSL varies based on line speeds.

DSL Cons
Many vendors, such as Dell and Compaq, are now selling computers with DSL modems. However, as it is with cable modems, DSL modems for one network may be incompatible with another network. Make sure your hardware and system requirements are clear before buying a modem.

Also, there are many factors that can affect DSL speed. For example, DSL modems can be plugged into the computer in different ways (via an internal card or a USB, for example). This may have an affect on the total bandwidth available to the computer. The premise wiring may also affect final DSL speed. Make sure your building wiring is good enough to handle the demands of high-speed data transmission.

Another limit to DSL speed is distance from the phone company's central office (CO). The greater the distance, the less the maximum speed. This distance limitation (less than 12,000 feet) makes it difficult to deploy DSL in large towns. Do not purchase any DSL equipment until you are told that you are close enough to the CO and that your internal phone lines are compatible with DSL (this is usually called Loop Qualification).

The biggest downside to DSL is installation. In many cases, there are 3 entities involved (the phone company, the DSL provider, and an ISP). Coordination of site visits and technician service can stretch out an installation over many months. It is not surprising that many of the top DSL companies seem to have serious financial difficulties.

One would think that the many local telephone companies (telcos) offering DSL might simplify the installation process. Unfortunately, telcos always seem to move more slowly than their competitors; a DSL installation by a telco may still take many months. I suggest that you agree upon an installation schedule before signing up with a DSL provider.

DSL Pricing
The price range for DSL services from different providers (and in different markets) is great. Installation and modem prices vary from $100 to $600. Speed prices vary based on the speed of service, but can be as low as $40 per month.

Both broadband cable and DSL offer simple, inexpensive access to high-speed data service. Which would I recommend? Let me pose a few questions first.

Which service is available in your area? Even if both services are available in your city or town, your location might preclude you from receiving either of them.

For example, with DSL, your distance from the phone company's CO dictates the maximum DSL speed you can get—and that could be zero (that is, if you're too far).

With cable, businesses are usually not wired for this traditionally residential service. Give the local cable company a call anyway.2

What are your data requirements? Let's say that both DSL and cable are available to you. You would need to decide how you expect to use your high-speed connection. Do you just need e-mail capability? Do you want to run web servers? Most cable services do not give subscribers a fixed internet address, which would be required for running a web server. But most DSL services allow you to purchase fixed addresses as an option.

Also, cable service usually comes with a single maximum data transmission speed. And, due to the shared nature of cable, the transmission speed might vary greatly.

In contrast, DSL is usually set to different transmission speeds that are usually dependable. You can then easily upgrade to a higher speed as your needs grow.

Symmetric or asymmetric DSL? Think about how much and what type of data is needed. If you are mostly downloading text information (browsing and light e-mail), then a slower asymmetrical service is sufficient, because there is no need for high upstream speed. If you regularly upload large files, such as graphics to a service bureau, then be mindful of the upstream speed.

How much can you afford? Cable is a good value for the speed of the connection, and usually has a low fixed monthly cost. DSL also is a good value, at any speed, and usually has a fixed monthly cost, too. But, the higher DSL speeds can be expensive—in the hundreds of dollars. Nonetheless, DSL is still much cheaper than similar high-speed services, such as ISDN and fractional T1.2

Comparison of Cable and DSL Service

Cable DSL
Speed 500-1500 Kbps downstream 128-500 Kbps upstream 128 Kbps-1.5 Mbps upstream and downstream*
Monthly costs Around $40 From about $40-$300
Initial costs $100-$200 $100-$600
Pros One price. High potential bandwidth. Can add phone and video services. Dedicated line. Always on, continuous connection. Over existing copper lines. Can share with phone service. Dedicated line. Always on, continuous connection.
Cons Shared network can cause performance and security problems. Limited service to businesses. Speed of connection dependent on distance from switching office. Potential installation delays.

*Speeds can be symmetric (SDSL) or asymmetric (ADSL)

Here are 3 good books providing overviews of the high-speed data access industries.

DSL for Dummies, by David F. Angell
Synopsis: An introduction to DSL in an approachable style. This book is targeted to large and small organizations, telecommuters, and IT professionals who wish to take advantage of this technology.

Residential Broadband: An Insider's Guide to the Battle for the Last Mile, by Kim Maxwell
Synopsis: A riveting historical and technical review of the new technologies being used to provide high-speed data access (standard modems, ISDN, various DSL flavors, and cable modems) in the "last mile" to residences and businesses. The author explains what will work and why.

Modern Cable Television Technology: Video, Voice, and Data Communications (Morgan Kaufmann Series in Networking), by James Farmer, David Large, Walter S. Ciciora
Synopsis: Three leading cable industry engineers have written a reference manual on broadband technology. This book provides a resource for information in the technical issues important in the modern cable industry. has lists of the deployment of broadband cable services by state and by vendor. (

2What if you can't get DSL or cable? If you're still itching for high-speed internet access, but the high cost of alternative services (T1 or ISDN) has you worried, ask yourself how much it would cost you NOT to have high-speed access. If faster data access can be translated into profit, then I say don't wait around for DSL or cable to be deployed in your area.