|CMTS||CMTS (Cable Modem Termination System) is a system of devices located at the head-end (the local cable TV company office) that exchanges digital signals with cable modems on a cable network. All cable modems can exchange signals only with the CMTS, and not directly with other modems.
One TV channel is used for upstream signals from cable modems to the CMTS, and another channel for downstream signals from the CMTS to cable modems. The CMTS is responsible for converting received signals into IP packets, which are then sent to an IP router for transmission across the Internet. When a CMTS sends signals to a cable modem, it modulates the downstream signals for tranmission to the cable modem via coax cable.