Configuring Headend Broadband Access Router Features

Configuring the Downstream Cable Interface

Configuring the Downstream Cable Interface

The first step in configuring the Cisco cable modem interface is to configure the downstream cable interface. The downstream direction refers to the data flow from the Cisco cable modem card in a Cisco uBR7200 series to the subscriber’s cable modem. Data passing through the Cisco cable modem card is converted to IF and then passed through an upconverter to transform the signal to RF. This RF signal is then sent down the line to the subscriber’s cable modem. Downstream cable interface commands configure the frequency, symbol rate, compression, and modulation of the downstream signal.

To configure the downstream cable interface, perform the following tasks:

Activating the Downstream Carrier

Setting the Downstream Center Frequency

Setting the Downstream Channel ID

Setting the Downstream MPEG Framing Format (Annex B)

Setting the Downstream Modulation

Setting the Downstream Interleave Depth

Setting the Downstream Helper Address

Setting Downstream Rate Limiting

Note In most applications, the default values for the commands used in these configuration steps are adequate to configure the Cisco uBR7200 series router.

Activating the Downstream Carrier

To activate a downstream port on a Cisco uBR7200 series cable modem card for digital data transmissions over the HFC network, use the following commands:

 

Command

Purpose

Step 1

 

 

CMTS01> enable

Enters enable (privileged EXEC) mode.

 

Password: <password>

Enters the password.

 

CMTS01#

 

 

You have entered privileged EXEC mode when the

 

 

prompt displays the pound symbol (#).

Step 2

 

 

CMTS01# configure terminal

Enters global configuration mode. You have entered

 

Enter configuration commands, one per line. End with

global configuration mode when the prompt displays

 

CNTL/Z.

(config)#.

 

CMTS01(config)#

 

 

 

 

This command can be abbreviated to config t.

Step 3

 

 

CMTS01(config)# interface cable 6/0

Enters cable interface configuration mode.

 

CMTS01(config-if)#

In this example, the interface is downstream port 0 on

 

 

 

 

the cable modem card installed in slot 6 of the

 

 

Cisco uBR7200 series.

 

 

 

Cisco IOS Multiservice Applications Configuration Guide

MC-535

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Cisco Systems uBR7200 manual Configuring the Downstream Cable Interface, Activating the Downstream Carrier, MC-535