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 ISDNeach 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.
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 broadband technology has a high theoretical bandwidth of 30 Mbpsmore
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
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
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 shareda 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.
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
Installation usually involves multiple visits so that the phone company, DSL
provider, and ISP can test the lines, install the equipment, and activate the
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.
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
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.
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
For example, with DSL, your distance from the phone company's CO
dictates the maximum DSL speed you can getand 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 expensivein 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
||500-1500 Kbps downstream 128-500 Kbps upstream
||128 Kbps-1.5 Mbps upstream and downstream*
||From about $40-$300
||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.
||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
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.
1CATV.org has lists of the deployment of broadband
cable services by state and by vendor. (http://www.catv.org)
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