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SDSL vs. Cable
Internet Access
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Cable Internet Access "Not Yet Ready" for Primetime
Now that many cable operators are offering "cable
modems" for Internet access, many businesses are looking
into using this service rather than dial-up, DSL or
private-line service.
While cable modem service is very attractive for personal use,
it's presently less attractive for businesses.
The cable plant is a shared facility - everyone in a
neighborhood shares the same bandwidth for services, just like
a local area network. A business customer could see a
substantial impairment of service in the afternoon while
teenagers swap MP3s with each other.
Cable modem service isn't available to all businesses. The
cable wiring is typically installed in residential
neighborhoods and doesn't connect to most businesses.
Cable operators don't have a good track record in providing
reliable service; service outages of days or weeks are sadly
not uncommon. Business instability has recently caused
millions of people to lose their email addresses - and in some
cases, lose their incoming email.
Finally, cable operators bundle ISP service with their cable
modem service. This often entails switching ISP provider
as well as transport provider. Businesses need to
carefully consider whether the cable operator can provide the
same quality of service as they're used to getting from their
present ISP.
At some time in the future, cable operators will deploy
technologies which will enable them to provide tiered
services, and will offer businesses a higher level of service
-- in terms of performance, reliability and support -- than
they offer consumers. And cable operators have started
interconnecting with outside ISPs. When both of these are in
place, business customers could seriously consider switching
to cable modem service.
DSL vs. Cable Modems
DSL technology is clearly a superior choice compared to cable
modems because DSL is more secure and can assure you access to
higher bandwidth on busy networks.
The actual "real world" available
bandwidth provided by a cable modem is affected, at times
severely, by how many other cable modem subscribers are using
the service at the same time. This is why cable modem service
is often advertised as "up to 100 times faster" than
traditional analog modems, and it is also why cable Internet
operators candidly admit "Actual speed experienced is
dependent on several factors including size of the file,
server congestion, neighborhood usage, etc."
According to Kieran Taylor, a broadband
industry consultant, each computer accessing the Internet via
cable modem on a segment of 100 homes would see throughput
drop to 500Kbps if every resident were using the network at
once. "It's still an increase over analog modems and even
ISDN, but we don't think it's enough." (quoted from America's
Network magazine)
A DSL connection is point-to-point, not
broadcast, so your bandwidth is precisely that: yours - in
terms of how much data you can send and receive, and in terms
of who sees it. Because cable modems utilize what is
essentially a broadcast technology, packets destined for your
cable modem (and ultimately your computer) are also sent to
every nearby subscriber's home or office. Their computers are
of course configured to examine these packets, determine that
they are not intended for their node on the network, and
discard them. It is a simple matter, however, to change this
configuration to "capture the traffic" of fellow
cable modem customers:
"The problem with cable modems is that
they are really network connections. Any two-way cable modem
system opens the network users to complete vulnerability. I've
already chatted with a friend who put a network snooping tool
on his cable modem-based Internet connection; he said it was
interesting to see what the preacher down the street was
downloading in the wee hours." -- John C. Dvorak of PC
Magazine
Also, who is going to give more personalized service?
A large conglomerate or a locally owned ISP?
