Amazingly, even with five traditional networks, six news channels, seven
shopping stations, eight sports channels, and a couple dozen strange offer-
ings that must be of interest to someone somewhere at sometime if not you,
there is still space on a television cable for two channels of the Internet.
(Why two? Most cable Internet offerings are unbalanced, meaning that the
download stream of web pages, audio, video, and e-mail is under heavier
demand than the upload stream of commands, e-mail, and whatever else you
might send from your machine to the rest of the world. In an unbalanced
system, more of the available bandwidth is made available to the incoming
stream than the uploading stream.)On the machine in my office, I typically receive a download speed of about
3mbps and an upload speed of about 236kbps. To put that in perspective,
when I am receiving a web page or a video feed, it is coming in at about
60 times faster than a dial-up modem could deliver; when I am uploading,
my data goes onto the Internet at speeds of four to six times faster than is
possible using POTS.Today, the download speed of a cable modem and a cable system varies from
about 1.5–4 Mbps with expectations that some more advanced systems will
reach 5 Mbps speeds in coming years.A number of technical designs (called protocols) exist for cable modem, but
nearly all current devices adhere to a standard called DOCSIS (Data Over
Cable Service Interface Specification).As a user, all that matters is that your
modem meets the requirements of the cable company; once you’re connected
to the Internet, it does not matter what type of modem is used by any person
or service you connect to. You may receive a free loan of a cable modem when
you contract with a cable company for the service or you may be required to
rent one from the company; it may be cheaper to buy your own cable modem,
although the cable company may decline to offer support for something it
did not provide.And the next step in the evolution of the use of the fat television cable is to
also bring in a telephone signal; among early major providers are Vonage and
AT&T (a distant cousin of the original Ma Bell). The technology is called VOIP,
for Voice Over Internet Protocol.You’ll add a telephone adapter to the cable
router. It will not be long before you can purchase a portable VOIP telephone
adapter to allow direct connection of your laptop to a cable television
Internet feed. (And just to make things a bit more complex, something called
digital telephone serviceuses a portion of the cable television line to carry
signals that, once they reach a switching office, are then routed over tradi-
tional telephone wires, satellite, or microwave connections.)To this point, I’ve written of nothing but good news. Cable modem users have
a few areas of possible concern:230 Part IV: Failing to Communicate