user manual

Configuring Headend Broadband Access Router Features
Configuring the Downstream Cable Interface
MC-540
Cisco IOS Multiservice Applications Configuration Guide
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
• Make sure the cable connections are not loose or disconnected.
• Make sure the Cisco cable modem card is firmly seated in its chassis slot and the captive installation
screws are tight.
• Make sure you 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.
Setting the Downstream Interleave Depth
Set the interleave depth for the downstream port on the Cisco 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:
Verifying the Downstream Interleave Depth
To verify the downstream interleave depth setting, enter the show controllers cable command for the
downstream port 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=
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
• Make sure the cable connections are not loose or disconnected.
• Make sure the Cisco cable modem card is firmly seated in its chassis slot and the captive installation
screws are tight.
• Make sure you entered the correct slot and port numbers when you typed the command.
• Make sure the downstream carrier is active by entering the cable downstream if-output command.
Command Purpose
CMTS01(config-if)# cable downstream interleave-depth
{8|16|32|64|128}
Sets the downstream interleave depth in
milliseconds.