Modem Momentum
If you're able, get cable.
Among the new waves of technology washing
ashore in recent years are cable modems - devices for gaining very
high-speed Internet access through a cable television network.High
bandwidth technologies like cable modems are important to teleworkers… if
the technology isn't as fast at home as in the office, then neither is the
worker.
AT&T has been investing heavily in
enhancing cable infrastructures, working to offer Internet, cable TV and
telephone access through these networks. At the heart of this strategy lies
the cable modem: Why is it needed? What is it? What does it do? How does it
do it? And how do you get one?
What is it?
While similar in some ways to the analog modem you may currently have, a
cable modem is much more powerful - theoretically, as much as up to 1,000
times faster. (Throughput, however, actually never reaches theoretical
speeds outside of controlled lab conditions, just as your 56k modem never
reaches its top-rated speed.)
What does it do?
A cable modem is still the fastest Internet service for your home. Adding to
the speed boost is the "always on" Internet connection that
doesn't require dialing in every time you want to go online. And you can
continue to receive television over the same cable, while data services can
be shared by up to sixteen PCs in a home-based LAN configuration.
How does it do it?
With cable modems, users served by a "node" (from 200-2000 homes,
depending on the provider) share the available bandwidth. A key component is
the central transmission facility, known as the "head-end".
Subscribers connect to the head-end, which connects to the Internet and to
satellite television transmission systems. Privacy and security, data
networking, and quality control are integrated into the network at the
head-ends.
Upstream and down.The
cable modem converts data signals into a form suitable for rapid
transmission. Data moving from the cable network to you is known as
"downstream" data, while "upstream" data moves from you
to the network. (Because most cable networks were built for television, some
cable modems use a telephone line to transmit data upstream.)
Downstream data is designed to move faster,
while upstream data is sent at variable speeds managed by the head-end. Data
rates can be configured to meet different user needs. For example, an
e-commerce business needs to send and receive at higher speeds, while a
residential user is normally set up to receive at a relatively high rate and
send at a slower one. After all, as a single user, most of what you're
sending "up" is keystrokes and mouse-clicks, whereas what's being
sent "down" to you is more substantial - text, images, streaming
audio and video, and so on.
The upstream data you send is placed on a
fiber optic backbone, which carries traffic across your regional provider.
This is the fastest part of the trip. Here, data moves at rates near the
speed of light. For the rest of the journey, your data may encounter slower
media - copper wire - as well as "choke points" where it has to
wait its turn. On the return trip, the head-end combines the downstream data
with the television video and audio and sends the composite signal to you.
The signal is re-divided at your house so that the television signal goes to
your TV and the Internet data goes to your PC.
In almost all cases, cable modem users
will see speeds that exceed an ISDN connection.
Performance:
A cable data network is similar to an office local area network (LAN) on a
larger scale. The local cable provider manages an extended Ethernet network
over a wide geographic area. If you were the only user served by a
neighborhood node on this network, you'd have all the bandwidth to yourself.
When all your neighbors also have cable modems, speeds go down somewhat -
just as heavy traffic slows down rush hour, a high volume of users on a node
reduces data throughput (especially if they're using lots of bandwidth to
view streaming media, for example). Cable providers will usually add a node
to an area to ease such congestion.
Some Internet content is cached (temporarily
stored) at the head-end to provide users with quicker access. Of course, not
all web content can be cached, and so your request may travel beyond the
head-end and across the Internet. Once you're beyond the head-end, you're on
the same Internet as everyone else and subject to the same delays. But in
almost all cases, cable modem users will see throughput to the cable
head-end and to the wider Internet at speeds that exceed those of an ISDN
connection.
While definitive statements about actual
speed are impossible, the perceptible difference between regular and cable
modems is dramatic. Web pages, especially "popular" ones, pop up
instantly. Large files download in seconds. Streaming audio and video
activate without perceptible delay. This all nets out (no pun intended) in
leaps in productivity - more working time and less "hourglass"
time.
I'll Take One! By now, you may be asking,
"So, where do I sign up?" You can begin by going to www.home.com,
the online source for @Home cable modem services. Click the highlighted link
for "Can I get @Home?" and enter your address to see if the
service is available in your area. If it's not yet available in your
neighborhood, @Home will contact you when it is.
