User's Manual

Note that DOCSIS permits multiple Upstream channels to work with a single Downstream
channel.
14.2 Ranging
The CMTS is not aware that a new cable modem has entered the system until it receives an
initial RF burst from the modem. As the CMTS receives this RF burst, it commands the
modem to increase or decrease its transmitter power. The CMTS’ receiver operates best
when all the cable modems RF is received at the same power level.
The CMTS assigns the modem an initial time slot.
14.3 Connection
After the initial communications link is set up at the RF level, the cable modem has to start
entering the system. The CMTS sends it information about the various servers it has to
interact with: the IP addresses for the DHCP, ToD and other servers.
14.4 Configuration
The CMTS sends the modem the standard modem configuration file, which includes an IP
address for the modem.
14.5 Registration
The cable modem initiates the registration process, which includes the class of service
subscribed to and the general Authentication, Authorization and Accounting class of
features and attributes.
Security is also handled during this phase, with RSA and DES encryption keys being
exchanged, as appropriate.
14.6 Maintenance
Periodically the entire cable system will go through recalibration of power levels, frequency
accuracy, channel assignments, load balancing, etc., all of which requires hand-shaking
between the cable modem and the CMTS.
June 2003 Page 14-2