Feature Overview

Table 3

Cable Access Router Initialization Sequences and Events (continued)

 

 

 

Sequence

Event

Description

 

 

 

4

Establish IP connectivity.

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.

 

 

Note The DHCP server is typically a dedicated server at the

 

 

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.

 

 

 

5

Establish the time of day.

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).

 

 

 

6

Establish security.

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.

 

 

 

7

Transfer operational parameters.

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.

 

 

Note The DOCSIS configuration file must be in the exact

 

 

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.

 

 

 

8

Perform registration.

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.

 

 

 

20Cisco IOS Release 12.0(7)T

Page 20
Image 20
Cisco Systems UBR900 specifications Cisco IOS Release 12.07T