Cisco uBR900 Series Configuring page 20

Feature Overview
Table 3
Sequence
4
5
6
7
8
20 Cisco IOS Release 12.0(7)T
Cable Access Router Initialization Sequences and Events (continued)
Event
Establish IP connectivity.
Establish the time of day.
Establish security.
Transfer operational parameters.
Perform registration.
Description
After the next MAP message broadcast, the router uses a
shared require timeslot to invoke Dynamic Host Configuration
Protocol (DHCP) to establish IP connectivity with the TCP/IP
network at the headend.
The DHCP server sends a response containing the router's IP
address as well as the IP addresses for the default gateway,
time of day (TOD) server, and Trivial File Transfer Protocol
(TFTP) server, and the DOCSIS configuration file to be
downloaded. Depending on the particular network
configuration, other information could be provided, such as
the IP addresses for a syslog server or security server.
The DHCP server is typically a dedicated server at the
Note
headend, but it could also be a CMTS such as a Cisco uBR7200
series universal broadband router.
The router configures itself for the specified IP address and
gets the current date and time from the specified TOD server.
The cable access router accesses the TOD server for the
current date and time, which is used to create time stamps for
logged events (such as those displayed in the MAC log file).
Full Security, a planned enhancement to Baseline Privacy, is
not fully defined nor currently supported by the DOCSIS
specification, and is therefore not supported by the
Cisco uBR900 series.
Using TFTP, the router downloads the specified DOCSIS
configuration file and configures itself for the appropriate
parameters. The DOCSIS configuration file defines the
router's operating mode such as the provisioned downstream
and upstream service assignments, including assigned
frequencies, data rates, modulation schemes, Class of Service
(CoS), type of services to support, and other parameters. Cisco
provides tools to help automate the creation of configuration
files.
The DOCSIS configuration file must be in the exact
Note
format given by the DOCSIS specification. An incorrect
DOCSIS configuration file can cause the Cisco uBR900 series
to constantly cycle offline. Such errors include wrong
downstream frequency, wrong UCD, wrong downstream
Channel ID, invalid CoS, incorrect BPI privacy configurations
or shared secret strings.
The cable access router sends another registration request to
the CMTS containing the CoS parameters given in the
DOCSIS configuration file.
The CMTS verifies that the router is using the appropriate CoS
profile and converts the temporary SID into a data SID with a
service class index that points to the applicable CoS profile.
The router completes its secondary ranging and is then online,
passing data between the HFC network and the PCs and other
CPE devices that are connected to the router.