Cable or DSL: Which Is for You?
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.
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
jack. On the other, it connects to the cable TV system network via
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
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
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
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.
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
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.
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
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
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
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
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
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
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
500-1500 Kbps downstream
128-500 Kbps upstream
128 Kbps-1.5 Mbps upstream
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,
network can cause performance and security problems. Limited
service to businesses.
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 area.