Hardware Reference
In-Depth Information
city, you might be able to choose from several broadband solutions. The first portion of this chapter
focuses on these solutions.
Cable TV
Cable TV (CATV)-based Internet piggybacks on the same CATV service lines used for cable
television service.
The device used to connect a PC to a CATV network is called a
cable modem
. In fact, the so-called
“cable modem” is actually a great deal more. The device does indeed modulate and demodulate, but
it also functions as a tuner, a network bridge, an encryptor, and a Simple Network Management
Protocol (SNMP) agent. To connect your PC to a CATV network, you do not use a serial port as with
dial-up modem technologies or Integrated Services Digital Network (ISDN) terminal adapters.
Instead, the most typical connection today runs the incoming cable connection to an external cable
modem, which has an Ethernet connection to a router, which then connects from 1-255 PCs via
Ethernet. Some cable modems have built-in router functionality, in which case you don't need to
purchase a separate one.
Tip
For maximum security, speed, and ease of sharing among multiple systems, I recommend that
you connect your cable modem (if it doesn't include its own router) to a router and then
connect the router to an Ethernet card or port in your system. Combination cable modems and
routers are available that include both functions in one box. These devices are sometimes
referred to as cable gateways.
Cable Modems
The cable modem connects to the CATV network using the same coaxial cable connection as the
cable TV service (see
Figure 16.1
). Thus, the cable modem functions as a bridge between your
network and the hybrid fiber/coax (HFC) network that connects all the cable customers in your
neighborhood.
