Chapter 4 Troubleshooting the System

Managing Cable Modems on the HFC Network

Tips The SNR estimate for a cable modem installed at a headend should be between 35 dB and 39 dB. Although the exact value displayed will vary from cable modem to cable modem, values collected on the same cable modem from measurement to measurement will be consistent. Maximizing SNR optimizes cable modem reliability and service quality.

Managing Cable Modems on the HFC Network

To manage cable modems connected to the network, perform the following as appropriate:

Configure Sync Message Interval

Activate Cable Modem Authentication

Activate Cable Modem Upstream Address Verification

Configure Dynamic Contention Algorithms (Cable Insertion Interval, Range, and Data Backoffs)

Configure the Dynamic Map Advance Algorithm

Configure Per Modem Filters

Configure the Maximum Number of Hosts Attached to a Cable Modem

Configure Cable Modem Registration Timeout

Clear Cable Modem Reset

Clear Cable Modem Counters

Configure Traffic Shaping

Configure Spectrum Management (without the Cisco MC16S Cable Modem Card)

Caution Cisco recommends using default values for most commands. Default settings are adequate for most systems.

Configure Sync Message Interval

To specify the interval between successive sync message transmissions from the Cisco uBR7200 series, use the following command in cable interface configuration mode.

Table 4-1

Instructions to Configure Sync Message Interval

 

 

 

 

Command

 

Purpose

 

 

CMTS01(config-if)#cable sync-interval msec

Specify the interval in milliseconds between

 

 

successive sync message transmissions from the

 

 

Cisco uBR7200 series. Valid values are from

 

 

1 to 200 msec. Default = 10 msec.

no cable sync-interval

Return the sync message interval to its default

 

 

value of 10 msec.

 

 

 

Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

4-2

78-5897-01

 

 

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Cisco Systems uBR7200 Series manual Managing Cable Modems on the HFC Network, Configure Sync Message Interval