Cisco Systems uBR7246 Manual De Usuario

Voice, Video, and Home Applications Configuration Guide

To set the downstream modulation, use the following command in cable interface configuration 
mode:

Validation Tips

To verify the downstream modulation setting, enter the show controllers cable command for the 
downstream port that you have just configured: 

router# show controllers cable 6/0 downstream

Cable6/0 Downstream is up

 Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps

 FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4

Troubleshooting Tips

If you are having trouble: 

•

Make sure the cable connections are not loose or disconnected. 

•

Make sure the cable modem card is firmly seated in its Cisco uBR7246 chassis slot.

•

Make sure that you have entered the correct slot and port numbers when you typed the command.

•

Make sure you have selected the default if you are not certain about the modulation rate needed.

•

Make sure the downstream carrier is active by entering the cable downstream if-output 
command.

Set the Downstream Interleave Depth

The next step is to set the interleave depth for a downstream port on a cable modem card. A higher 
interleave depth provides more protection from bursts of noise on the HFC network; however, it will 
increase downstream latency. The valid values are 8, 16, 32 (default), 64, and 128. 

To set the downstream interleave depth, use the following command in cable interface configuration 
mode: 

Validation Tips

To verify the downstream interleave depth setting, enter the show controllers cable command for 
the downstream port that you have just configured: 

router# show controllers cable 6/0 downstream

Cable6/0 Downstream is up

 Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps

 FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=

Set the standard MCNS rate.

{8 | 16 | 32 | 64 | 128}

Set the downstream interleave depth.