Internet Access Guide : Cable Modem
Internet access using cable modem is an always-on connection that's once a computer
is connected to a CATV network
through a cable modem, the computer is always connected to the
Internet every time it is turned on. But as in ADSL, nowadays most
ISPs offer an option to use log-in process when trying to access
the Internet using a cable modem. This is implemented using
PPPoE or
PPPoA. It derives all PPP features but runs over
Ethernet or ATM interface on the cable TV network.
Internet access over CATV network often requires a prior
cable TV subscription to the cable TV operator. Most cable
TV operators today offer Internet access. In the
early days of Internet
access using cable modem there were concerns over data privacy and security because the
fact that the cable is shared among neighbors sometimes caused one
to be able to sneak his neighbor's computer data and learn what websites she
had visited
on the Internet. But with DOCSIS this problem is overcome by
encrypting the communication between cable modem and CMTS.
In most cases, cable Internet access service is charged with a flat monthly
rate. But a cable TV operator or ISP may also charge its customers
based on usage (downloaded/uploaded bytes or connection time). The
ISP usually provides a cable modem for a flat monthly
rental fee. But, if you think it is cheaper to buy a cable modem in
your subscription plan, then buy one which is compatible
with your cable operator's modem standard.
Cable Modem Internet Access |
User Equipment |
Cable modem, Ethernet card (if the cable modem connects through Ethernet port) |
Operator Equipment |
CMTS |
Modem Standard |
DOCSIS 1.0, 1.1, 2.0 |
Maximum Downstream Data Rate |
38 Mbps (shared) |
Maximum Upstream Data Rate |
30 Mbps (shared) |
Connection |
always-on; log-in (PPPoE/PPPoA) |
Charging |
Flat monthly rate plus cable modem rental fee (optional)
or usage-based (transferred bytes or connection time) |
Simultaneous Service |
Cable TV |
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