Hardware: Cable Modems

Starting from the home, a cable internet connection begins with, of
course, a PC with an Ethernet card (most times) connected to a cable
modem, usually through a router using 10 base T/100 base T, cat 5
or 6 networking cable. The cable modem performs two tasks. The
cable modem sends and receives packets from the CMTS. Received
data arrives at the cable modem in MPEG packets (strange, I know).
However, data is sent from the cable modem in IP packets. So, now
we begin to describe the equipment past the cable modem or
transceiver.

Cable Modem Termination System (CMTS)
The cable modem communicates with the CMTS. The CMTS operates
much like the DSLAM. It pools the connections of hundreds to
thousands of cable subscribers. Current arguments suggest that cable
Internet access limited to the number of users in a neighborhood.
While it is true that the number of users in a neighborhood share the
bandwidth of the neighborhood cable Internet connection the
slowing of the Internet connection with additional subscribers is only
partially true. The cable provider will only allow a particular CMTS to
carry subscribers until the Internet connection drops off. When this
happens the cable Internet service provider upgrades the CMTS to
handle more subscribers while maintaining advertised speeds.
Between the cable modem and CMTS is a network of hybrid
coax-fiber optic (HFC) cables. The CMTS is located at the CATV head
end.

Head-End
The Head-End is simply a facility where the cable company keeps the
equipment like the CMTS. The Head-End is like the Central office of
DSL except distance is not as important because cable Internet
service utilizes amplifiers that are able to boost the signal over
longer distances to the Head-end and into the CMTS.