4-2
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
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Chapter4 Troubleshooting the System
Managing Cable Modems on the HFC Network
Tips TheSNR estimate for a cable modeminstalled at a headend should be between 35 dBand
39 dB. Although the exact valuedisplayed 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 Ciscorecommends using default values for most commands. Default settings are adequate
for most systems.

Configure Sync Message Interval

Tospecify the interval between successive sync message transmissions from the Cisco uBR7200 series,
use the following command in cable interface configuration mode.
Table4-1 Instructions to Configure Sync Message Interval
Command Purpose
CMTS01(config-if)#cable sync-interval
msec
no cable sync-interval
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.
Return the sync message interval to its default
value of 10 msec.