There are more than seven million cable modem subscribers in the United States and Canada, and nearly all of them lease a proprietary modem from their cable company. The most widely used units: Motorola’s CyberSURFR, Nortel’s LANcity LCP, Com21’s ComPORT and Terayon’s TeraPro.
Each of these modems connects to a subscriber’s computer through a standard 10Base-T Ethernet link. An Ethernet card must be installed in the computer and connected to the modem through Category 5 UTP (unshielded twisted pair) wiring. That creates a 10-mbps link between the modem and the computer.
The Shift to Standards The development of standards-based cable modems is good news for consumers, because it yields more product choices, innovative features, and lower prices. Standards also ensure that products from different manufactures are compatible. In other words, if you move across town or across the country, the cable modem that worked with your old cable TV operator will work on your new cable service provider’s network.
Nortel LANcity LCP
The North America cable modem standard is called DOCSIS (Data Over Cable Service Interface Specification), and the first units to win that certification began to roll off the assembly line in 1999. A few cable companies are now selling DOCSIS modems at retail outlets like Circuit City. Prices range from $120 to $200.
Cable Television Laboratories, Inc., an industry research and development organization, is conducting rigorous testing for DOCSIS modems to guarantee that products are compatible. Cable modems that pass the test are labeled “CableLabs Certified” and feature the following logo on the product packaging. Be sure to look for this label when buying a cable modem.
Some 20 companies are manufacturing DOCSIS modems, including 3Com, Cisco, Com21, General Instrument, Nortel, Philips, Samsung, Sony, Toshiba and Thomson.
Toshiba DOCSIS Modem
3Com Home Connect
Many of their units will support plug-and-play USB (Universal Serial Bus) connections, which will eliminate the need for an Ethernet card in your computer. What’s more, manufacturers are developing cable modem cards that can be built directly into PCs, eliminating the need for an external device.