Number 199 - December 1999

Cable Modems Demystified
by Jennifer Fulton http://www.ivillage.com/click/experts/computingcoach/archive
How do you use a cable modem to connect to the Internet? This ... article reveals what you need to know to understand this latest Internet phenomenon.     With cable modem service, you don't dial up to connect to the Internet--instead, you have what's called a persistent connection.     Before I begin, let me explain what I'm talking about. In some areas of the country (maybe even in your hometown), it may be possible to connect to the Internet not through your telephone line, but through the coaxial cable that supplies cable TV (CATV) service to your home. In this case, your Internet Service Provider (or ISP) would be your television cable provider.     So how does cable modem service work? Well, first of all, your cable company has to offer this service (not all do just yet, though they probably will soon!). Then, instead of using the modem you've got now, you'll use something called a 'cable modem'. Like the cable box that some of us use to get cable transmission on a non-cable ready TV, a cable modem is not something you buy, but something you rent from your friendly neighborhood cable company. With cable modem service, you don't dial up to connect to the Internet--instead, you have what's called a persistent connection. Just like the cable on your television, where you simply turn the TV on, and you're watching cable, you simply turn on your computer, and you're connected to the Internet. Couldn't be any easier! What a Cable Modem Is Not     Funny thing is, a cable modem is not actually a modem at all. It's really a network switching device, of the sort you'd find on a local area network (LAN). On a LAN, a switching device normally allocates the maximum bandwidth (space) available at the time to each computer on a network as it needs it, rather than assigning a preset amount of space to each computer.	For cable modem service, the switching device makes sure that you get as much bandwidth as you need when you need it (as long as that space is available for use at the time). The cable modem is connected to your computer through a network interface card, or NIC, which the cable company installs for you.1 The cable company then runs a cable (10Base2 network cable) from your cable box (located typically on the outside of your house--your cable television is already connected to it) to your cable modem. The cable modem can be attached to as many as four computers. Another cable is run from the cable modem to the NIC connector at the back of your computer. The cable that is used for this part of the journey is called a CAT5 Ethernet cable, and it looks kind of like a telephone cable, only thicker. What You Do     Well, nothing, as it turns out. The cable people install the NIC card [or USB Ethernet Adapter -ed] in your computer, and setup the software that gets Windows to recognize it. Windows, by the way, does not need to know that the card will eventually be connected to a cable modem; all it will concern itself with is talking to the network interface card. After installing the NIC, the cable company connects the cable modem to the cable box, and then to your computer.     All you have to do is turn your computer on, start your Web browser, and you're on the Net--no waiting, no endless busy signals, no cursing your former ISP.     1 Or external USB Ethernet adapter, see footnote in previous article "Speed Up Slow Web Connections". - ed.
Number 199 - December 1999